The present invention relates to a silver halide photographic light-sensitive material. Specifically, the invention is concerned with a silver halide photographic light-sensitive material which, though it has an increased photographic sensitivity, is improved in not only fog caused by increasing the photographic sensitivity but also storage fog arising from storage under severe conditions.
In order to increase the intrinsic sensitivity of silver halide, a wide variety of methods have been adopted. For instance, the sensitivity increase is achieved by the use of chemical sensitizers, such as sulfur compounds, gold compounds and compounds of the group VIII metals, the combined use of those chemical sensitizers and additives enhancing their sensitizing effects, or the addition of additives capable of producing sensitizing effects depending on the species of a silver halide emulsion. Further, the sensitization techniques using organic electron donating compounds in which both electron donating group and releasing group are present are reported in U.S. Pat. Nos. 5,747,235 and 5,747,236, EP-A-786692, EP-A-893731, EP-A-893732 and WO99/05570. On the other hand, the fog accompanying a sensitivity increase and the storage fog arising from the storage under severe conditions, e.g., under circumstances of high temperature and high humidity, or in atmospheres of harmful gases produced by combustion, such as automobile exhaust gases, become problems. As compounds usable for inhibiting the fog generation, there are known mercaptotetrazoles, tetraazaindenes and the salts of thiosulfonic acid (Research Disclosure, Item 36544 (vol. 365, September in 1994), Section IV). The compounds recited above are however insufficient to inhibit the fog from generating with an increase of sensitivity, or conversely result in interference on the sensitivity increase. In other words, their effects are unsatisfactory. In addition, those compounds have little effects on the storage fog which generates upon storage under severe conditions, e.g., under circumstances of high temperature and high humidity, or in atmospheres of harmful gases produced by combustion, such as automobile exhaust gases. Therefore, it becomes an important subject to achieve the inhibition of the fog generation accompanying an sensitivity increase and the control of the storage fog. As other means for inhibiting the fog generation while increasing the sensitivity, the following are known.
As one means, it has been reported to combine certain sensitizers with organic compounds in themselves having very little or no sensitizing effect, thereby achieving both sensitization effect and storage stability. As examples of such a case are reported the chemical sensitization in the presence of 6-hydroxypurine in JP-B-7-11684 (the term xe2x80x9cJP-Bxe2x80x9d as used herein means an xe2x80x9cexamined Japanese patent publicationxe2x80x9d) the combinations of tellurium sensitizers with polymeric thioethers in JP-A-6-59362 (the term xe2x80x9cJP-Axe2x80x9d as used herein means an xe2x80x9cunexamined published Japanese patent applicationxe2x80x9d), the combinations of selenium sensitizers with hydrazine compounds in JP-A-6-19035 and JP-A-6-202262, and the combinations of tellurium sensitizers with hydrazine compounds in JP-A-5-333469.
As another means, the compounds which in themselves has no function as a sensitizer but can increase the sensitivity and control the fog generation when added to a silver halide emulsion layer have been reported.
Examples of such compounds include the thioether compounds disclosed in JP-B-6-56473, JP-A-1-12184, JP-A-1-121846, JP-B-7-11684 and Registered Japanese Patent No. 2,604,240, ascorbic acid the derivatives thereof as disclosed in Registered Japanese Patent Nos. 2,505,262 and 2,578,188, the silver halide adsorbing hydroquinone compounds disclosed in Registered Japanese Patent No. 2,641,982, the mercapto compounds disclosed in JP-A-5-134345, the benzothiazolium salts and thiosulfonic acids disclosed in JP-A-6-161019, and the thiourea dioxide compounds disclosed in JP-A-7-92591. Even when these compounds are used, however, the sensitization effects obtained are small, and the storage fog and the fog generation accompanying a sensitivity increase are not inhibited to a satisfactory extent.
Therefore, an object of the invention is to provide a silver halide photographic emulsion having improved sensitivity and keeping quality and, more specifically, to provide a silver halide photographic light-sensitive material which has an increased photographic sensitivity but control fog generation accompanying the increase in photographic sensitivity and has reduced storage fog even when stored under severe conditions, such as under circumstances of high temperature and high humidity, or in atmospheres of harmful gases generating upon combustion, such as automobile exhaust gases.
The object mentioned above is attained with a silver halide photographic light-sensitive material having a silver halide emulsion layer that is chemically sensitized by an organic electron-donating compound and improved in storage properties by containing a weakly reducing compound.
More specifically, the following are embodiments of the invention:
1. A silver halide photographic light-sensitive material having at least one emulsion layer comprising silver halide grains, with the emulsion layer further comprising at least one compound represented by the following formula (I) and at least one compound represented by the following formula (II), (III), (IV-1), (IV-2), (V-1), (V-2), (V-3) or (VI):
(X"Parenclosest"1"Parenopenst"L"Parenclosest"m"Parenopenst"Axe2x80x94B)nxe2x80x83xe2x80x83(I)
wherein X represents a silver halide adsorbing group containing at least one N, S, P, Se or Te atom, or a light absorbing group; L represents a divalent linkage group comprising at least one C, N, S or O atom; A represents an electron donating group; B represents a releasing group; 1 and m each represents 0, 1, 2 or 3; and n represents 1 or 2; 
wherein R1, R2, R3 and R4, which are independent of each other, each represents a hydrogen atom, an aryl group, a chain or cyclic alkyl group, a chain or cyclic alkenyl group, or an alkynyl group; and R5 represents a chain or cyclic alkyl group, a chain or cyclic alkenyl group, an alkynyl group, an aryl group or a heterocyclic group;
(Het"Parenclosest"k1"Brketopenst""Parenopenst"Q1"Parenclosest"k2"Parenopenst"Hy)]k3xe2x80x83xe2x80x83(III)
wherein Het represents a group enabling the adsorption to silver halide grains; Q1 represents a divalent linkage group made up of an atom or atomic group comprising at least one carbon, nitrogen, sulfur or oxygen atom; Hy represents a group having a hydrazine structure represented by R6R7Nxe2x80x94NR8R9; R6, R7, R8 and R9, which are independent of each other, each represents an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group, or R6 and R7, R8 and R9, R6 and R8, or R7 and R9 may combine with each other to complete a ring, provided that at least one among R6, R7, R8 and R9 is an alkylene group, an alkenylene group, an alkynylene group, an arylene group or a divalent heterocyclic ring residue to which xe2x80x94(Q1)k2(Het)k1 is attached; k1 and k3 each represents 1, 2, 3 or 4; and k2 represents 0 or 1; 
wherein R10, R11, R12 and R13, which are independent of each other, each represents a hydrogen atom or a substituent group, provided that, when the substituent groups represented by R10 and R13 or those represented by R11 and R12 are both alkyl groups, the number of carbon atoms contained in one alkyl group is different from that in the other; R14, R15 and R16, which are independent of each other, each represents a hydrogen atom or a substituent group; and Z represents nonmetal atoms completing a 4- to 6-membered ring; 
wherein Ra1 represents a substituted or unsubstituted alkyl group, an alkenyl group or an aryl group, Ra2 represents a hydrogen atom or a group represented by Ra1, and Ra3 represents a hydrogen atom, a substituted or unsubstituted alkyl group containing 1 to 10 carbon atoms or a substituted or unsubstituted alkenyl group containing 1 to 10 carbon atoms, or any two of Ra1, Ra2 and Ra3 combine with each other to complete a 5- to 7-membered ring; Xa represents a heterocyclic group and Rb1 represents an alkyl group, an alkenyl group or an aryl group, or Xa and Rb1 combine with each other to complete a 5- to 7-membered ring; Y represents nonmetal atoms forming a 5-membered ring in combination with the xe2x80x94Nxe2x95x90Cxe2x80x94 moiety, or nonmetal atoms forming a 6-membered ring in combination with the xe2x80x94Nxe2x95x90Cxe2x80x94 moiety wherein the end group of Y bonded to the carbon atom of the xe2x80x94Nxe2x95x90Cxe2x80x94 moiety is a group selected from the class consisting of xe2x80x94N(Rc1)xe2x80x94, xe2x80x94C(Rc2) (Rc3)xe2x80x94, xe2x80x94C(Rc4)xe2x95x90, xe2x80x94Oxe2x80x94 and xe2x80x94Sxe2x80x94 (which are each bonded to the carbon atom of xe2x80x94Nxe2x95x90Cxe2x80x94 on the left side); and Rc1 to Rc4, which are independent of each other, each represents a hydrogen atom or a substitutent group; 
wherein R17, R18 and R19, which are independent of each other, each represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group or a heterocyclic group, R20 represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a heterocyclic group or xe2x80x94NR21R22, L1 represents xe2x80x94COxe2x80x94 or xe2x80x94SO2xe2x80x94, n represents 0 or 1, R21 represents a hydrogen atom, a hydroxyl group, an amino group, an alkyl group, an alkenyl group, an alkynyl group, an aromatic group or a heterocyclic group, R22 represents an alkyl group, an alkenyl group, an alkynyl group, an aromatic group or a heterocyclic group, or R17 and R18, R17 and R19, R19 and R20, or R20 and R18 combine with each other to complete a ring.
2. A silver halide photographic light-sensitive material as described in Embodiment 1, wherein the silver halide grains are sensitized by a compound represented by formula (I).
3. A silver halide photographic light-sensitive material as described in Embodiment 1, wherein the compound represented by formula (I) has an oxidation potential of from 0 to 1.5 V.
4. A silver halide photographic light-sensitive material as described in Embodiment 1, wherein the moiety Axe2x80x94B in the compound represented by formula (I), when it takes an oxidation form, undergoes bond cleavage reaction to produce a radical A. having an oxidation potential of xe2x88x920.6 V or below and a releasing fragment B.
5. A silver halide photographic light-sensitive material as described in Embodiment 1 or 2, wherein at least 60% of the silver halide grains in said at least one emulsion layer on a projected area basis are tabular silver halide grains having an aspect ratio of at least 8.
The compounds used in the present invention are illustrated below in detail.
The silver halide adsorbing group represented by X in formula (I) contains at least one N, S, P, Se or Te atom, and preferably has a silver ion ligand structure. Suitable examples of a group having such a silver ion ligand structure include groups represented by the following formulae (X-1), (X-2a), (X-2b), (X-3), (X-4), (X-5a), (X-5b), (X-6a) and (X-6b) respectively. Additionally, it is desirable that the pKa of the compounds as recited below be from 3 to 14.
xe2x80x94G1xe2x80x94Z1xe2x80x94R23xe2x80x83xe2x80x83(X-1)
wherein G1 represents a divalent linkage group, with examples including a substituted or unsubstituted alkylene group, a substituted or unsubstituted alkenylene group, a substituted or unsubstituted alkynylene group, a substituted or unsubstituted arylene group, a substituted or unsubstituted sulfonyl group and a substituted or unsubstituted divalent heterocyclic group; Z1 represents an S, Se or Te atom; and R23 represents a hydrogen atom, or a sodium, potassium, lithium or ammonium ion as a counter ion necessitated when Z1 has a dissociation form; 
wherein a 5- to 7-membered heterocyclic or unsaturated ring is formed, Za represents an O, N, S, Se or Te atom, n represents 0, 1, 2 or 3, and R24 represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group or an aryl group;
xe2x80x94R25xe2x80x94(Z2)nxe2x80x94R26xe2x80x83xe2x80x83(X-3)
wherein Z2 represents an S, Se or Te atom, n represents 1, 2 or 3, R25 represents an alkylene group, an alkenylene group, an alkynylene group, an arylene group or a divalent heterocyclic group, and R26 represents an alkyl group, an aryl group or a heterocyclic group; 
wherein R27 and R28, which are independent of each other, each represents an alkyl group, an alkenyl group, an aryl group or a heterocyclic grouop; 
wherein Z3 represents an S, Se or Te atom; E1 represents a hydrogen atom, NH2, NHR31, N(R32)2, NHN(R32)2, OR32 or SR32; E2 represents NH, NR32, NHNR32, O or S; R29, R30 and R31, which are independent of each other, each represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group or a heterocyclic group, or R30 and R31 combine with each other to complete a ring; and R32 represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group or a heterocyclic group; 
wherein R33 represents a divalent linkage group, including an alkylene group, an alkenylene group, an alkynylene group, an arylene group and a divalent heterocyclic group; G2 and J, which are independent of each other, each represents COOR34, SO2R34, COR34, SOR34, CN, CHO or NO2; and R34 represents an alkyl group, an alkenyl group or an aryl group.
The groups represented by formula (X-1) are described in more detail. As examples of a linkage group represented by G1, mention may be made of a substituted or unsubstituted straight-chain or branched alkylene group containing 1 to 20 carbon atoms (such as methylene, ethylene, trimethylene, isopropylene, tetramethylene, hexamethylene, 3-oxapentylene or 2-hydroxytrimethylene), a substituted or unsubstituted cycloalkylene group containing 3 to 18 carbon atoms (such as cyclopropylene, cyclopentylene or cyclohexylene), a substituted or unsubstituted alkenylene group containing 2 to 20 carbon atoms (such as ethenylene or 2-butenylene), an alkynylene group containing 2 to 10 carbon atoms (such as ethynylene) and a substituted or unsubstituted arylene group containing 6 to 20 carbon atoms (such as unsubstituted p-phenylene or unsubstituted 2,5-naphthylene group).
Examples of a sulfonyl group represented by G1 include xe2x80x94SO2xe2x80x94 groups to which a substituted or unsubstituted straight-chain or branched alkylene group containing 1 to 10 carbon atom, a substituted or unsubstituted cyclic alkylene group containing 3 to 6 carbon atoms and a substituted or unsubstituted straight-chain or branched alkenylene group containing 2 to 10 carbon atoms are attached respectively.
Examples of a divalent heterocyclic group represented by G1 include a divalent unsubstituted heterocyclic group, a heterocyclic group substituted by an alkylene group, an alkenylene group, arylene group or a divalent heterocyclic group, and a benzene ring-condensed or naphthalene ring-condensed divalent heterocyclic group. (As examples of a heterocyclic group contained in the substituted or ring-condensed group as recited above, mention may be made of 1,5-tetrazole-diyl, 3,5-triazole-diyl, 1,2-imidazole-diyl, 2,5-oxadiazole-diyl, 2,4-thiazole-diyl, 2,6-benzimidazole-diyl, 2,6-benzothiazole-diyl, 2,6-benzoxazole-diyl, 2,4-pyrimidine-diyl, 1,5-(3-phenyltetrazole)-diyl, 3,5-pyridine-diyl, 3,4-furan-diyl, 2,5-piperidine-diyl and 2,5-morpholine-diyl groups.)
G1 in formula (X-1) may have all possible substituent groups. Examples of such substituent groups are recited below Herein, each of them is referred to as substituent Y.
More specifically, examples of Y includes a halogen atom (such as fluorine, chlorine or bromine atom), an alkyl group (e.g., methyl, ethyl, isopropyl, n-propyl or t-butyl), an alkenyl group (such as allyl or 2-butenyl), an alkynyl group (such as propargyl), an aralkyl group (such as benzyl), an aryl group (such as phenyl, naphthyl or 4-methylphenyl), a heterocyclic group (such as pyridyl, furyl, imidazolyl, piperidyl or morpholinyl), an alkoxy group (such as methoxy, ethoxy, butoxy, 2-ethylhexyloxy, ethoxyethoxy or methoxyethoxy), an aryloxy group (such as phenoxy or 2-naphthyloxy), an amino group (such as unsubstituted amino, dimethylamino, diethylamino, dipropylamino, dibutylamino, ethylamino or anilino), an acylamino group (such as acetylamino or benzoylamino), an ureido group (such as unsubstituted ureido or N-methylureido), an urethane group (such as methoxycarbonylamino or phenoxycarbonylamino), a sulfonyl-amino group (such as methylsulfonylamino or phenyl-sulfonylamino), a sulfamoyl group (such as unsubstituted sulfamoyl, N,N-dimethylsulfamoyl or N-phenylsulfamoyl), a carbamoyl group (such as unsubstituted carbamoyl, N,N-diethylcarbamoyl or N-phenylcarbamoyl), a sulfonyl group (such as mesyl or tosyl), a sulfinyl group (such as methylsulfinyl or phenylsulfinyl), an alkyloxycarbonyl group (such as methoxycarbonyl or ethoxycarbonyl), an aryloxycarbonyl group (such as phenoxycarbonyl), an acyl group (such as acetyl, benzoyl, formyl or pivaroyl), an acyloxy group (such as acetoxy or benzoyloxy), a phosphamido group (such as N,N-diethylphosphamido), a cyano group, a sulfo group, a thiosulfonic acid group, a sulfinic acid group, a carboxyl group, a hydroxyl group, a phosphono group, a nitro group, an ammonio group, a phosphonio group, a hydrazino group and a thiazolino group. When G1 has two or more substituents, they may be the same or different. And the substituents as recited above may further be substituted by another group.
Desirable examples of a silver halide adsorbing group of formula (X-1) are described below.
The groups desirable for G1 in formula (X-1) are a substituted or unsubstituted arylene group containing 6 to 10 carbon atoms and an unsubstituted, alkylene or arylene-attached, or benzene or naphthalene ring-condensed 5 to 7-membered heterocyclic group. The atoms desirable for Z1 are S and Se atoms. As to R23, hydrogen atom, sodium ion and potassium ion are desirable.
It is more desirable for G1 to be a substituted or unsubstituted arylene group containing 6 to 8 carbon atoms or an arylene-attached or benzene ring-condensed 5- or 6-membered heterocyclic group. The most desirable G1 is an arylene-attached or benzene ring-condensed 5- or 6-membered heterocyclic group. The preferred Z1 is S, and the preferred R23 is a hydrogen atom or sodium ion.
Formulae (X-2a) and (X-2b) are illustrated below in detail.
Examples of an alkyl, alkenyl or alkynyl group represented by R24 include substituted or unsubstituted straight-chain or branched alkyl groups containing 1 to 10 carbon atoms (such as methyl, ethyl, isopropyl, n-propyl, n-butyl, t-butyl, 2-pentyl, n-hexyl, n-octyl, t-octyl, 2-ethylhexyl, 2-hydroxyethyl, 1-hydroxyethyl, diethylaminoethyl, n-butoxypropyl or methoxymethyl), substituted or unsubstituted cyclic alkyl groups containing 3 to 6 carbon atoms (such as cyclopropyl, cyclopentyl or cyclohexyl), alkenyl groups containing 2 to 10 carbon atoms (such as allyl, 2-butenyl or 3-pentenyl), alkynyl groups containing 2 to 10 carbon atoms (such as propargyl or 3-pentynyl) and aralkyl groups containing 6 to 12 carbon atoms (such as benzyl). Examples of an aryl group as R24 include substituted or unsubstituted aryl groups containing 6 to 12 carbon atoms (such as unsubstituted phenyl or 4-methylphenol).
Each of the groups recited above as R24 may further have a substituent Y.
Of the groups represented by formulae (X-2a) and (X-2b) respectively, the following are desirable.
In each formula, it is desirable that R24 be a hydrogen atom, a substituted or unsubstituted alkyl group containing 1 to 6 carbon atoms or a substituted or unsubstituted aryl group containing 6 to 10 carbon atoms, Za be O, N or S and n be from 1 to 3.
Preferably, R24 is a hydrogen atom or an alkyl group containing 1 to 4 carbon atoms, Za is N or S, and n is 2 or 3.
Formula (X-3) is illustrated below in detail.
Therein, the linkage group represented by R25 includes substituted or unsubstituted straight-chain or branched alkylene groups containing 1 to 20 carbon atoms (such as methylene, ethylene, trimethylene, isopropylene, tetramethylene, hexamethylene, 3-oxapentylene and 2-hydroxytrimethylene), substituted or unsubstituted cyclic alkylene groups containing 3 to 18 carbon atoms (such as cyclopropylene, cyclopentylene and cyclohexylene), substituted or unsubstituted alkenylene groups containing 2 to 20 carbon atoms (such as ethenylene and 2-butenylene), alkynylene groups containing 2 to 10 carbon atoms (such as ethynylene), substituted or unsubstituted arylene groups containing 6 to 20 carbon atoms (such as unsubstituted p-phenylene and unsubstituted 2,5-naphthylene) and divalent heterocyclic groups which each have no substitutent or an alkylene, alkenylene, arylene or heterocyclic substituent (such as divalent groups derived from pyridine, 3-phenylpyridine, piperidine and morpholine respectively).
In the formula, the alkyl group represented by R26 includes substituted or unsubstituted straight-chain or branched alkyl groups containing 1 to 10 carbon atoms (such as methyl, ethyl, isopropyl, n-propyl, n-butyl, t-butyl, 2-pentyl, n-hexyl, n-octyl, t-octyl, 2-ethylhexyl, 2-hydroxyethyl, 1-hydroxyethyl, diethylaminoethyl, dibutylaminoethyl, n-butoxymethyl and methoxymethyl) and substituted or unsubstituted cycloalkyl groups containing 3 to 6 carbon atoms (such as cyclopropyl, cyclopentyl and cyclohexyl), and the aryl group as R26 includes substituted or unsubstituted aryl groups containing 6 to 12 carbon atoms (such as unsubstituted phenyl and 2-methylphenyl).
The heterocyclic group as R26 includes heterocyclic groups which each have no substitutent or an alkyl, alkenyl, aryl or heterocyclic substituent (such as pyridyl, 3-phenylpyridyl, piperidyl and morpholinyl).
Each of the groups as R26 as recited above may have a substitutent Y.
Of the groups represented by formula (X-3), the following are desirable.
In the formula, it is desirable that R25 be a substituted or unsubstituted alkylene group containing 1 to 6 carbon atoms or a substituted or unsubstituted arylene group containing 6 to 10 carbon atoms, R26 be a substituted or unsubstituted alkyl group containing 1 to 6 carbon atoms or a substituted or unsubstituted aryl group containing 6 to 10 carbon atoms, Z2 be S or Se and n be 1 or 2.
Preferably, R25 is an alkylene group containing 1 to 4 carbon atoms, R26 is an alkyl group containing 1 to 4 carbon atoms, Z2 is S, and n is 1.
Formula (X-4) is illustrated below in detail.
Therein, the alkyl group represented by R27 and R28 each includes substituted or unsubstituted, straight-chain or branched alkyl groups containing 1 to 10 carbon atoms (e.g., methyl, ethyl, isopropyl, n-propyl, n-butyl, t-butyl, 2-pentyl, n-hexyl, n-octyl, t-octyl, 2-ethylhexyl, hydroxymethyl, 2-hydroxyethyl, 1-hydroxyethyl, diethylaminoethyl, dibutyl-aminoethyl, n-butoxymethyl, n-butoxypropyl, methoxymethyl) and substituted or unsubstituted cyclic alkyl groups containing 3 to 6 carbon atoms (e.g., cyclopropyl, cyclopentyl, cyclohexyl); the alkenyl group represented by R27 and R28 each includes alkenyl groups containing 2 to 10 carbon atoms (e.g., allyl, 2-butenyl, 3-pentenyl); the aryl group represented by R2 and R2 each includes substituted or unsubstituted aryl groups containing 6 to 12 carbon atoms (e.g., unsubstituted phenyl, 4-methylphenyl); and the heterocyclic group represented by R27 and R28 each includes heterocyclic groups which each have no substituent or an alkyl, alkenyl, aryl or heterocyclic substituent (e.g., pyridyl, 3-phenylpyridyl, furyl, piperidyl, morpholinyl).
Each of the above-recited groups as R27 and R28 each may further have a substitutent Y.
Of the groups represented by formula (X-4), the following are desirable
In formula (X-4), it is desirable that R27 and R28 each be a substituted or unsubstituted alkyl group containing 1 to 6 carbon atoms or a substituted or unsubstituted aryl group containing 6 to 10 carbon atoms, preferably an aryl group containing 6 to 8 carbon atoms.
Formulae (X-5a) and (X-5b) are illustrated below in detail.
Examples of a group represented by E1 in formula (X-5a) include NH2, NHCH3, NHC2H5, NHPh, N(CH3)2, N(Ph)2, NHNHC3H7, NHNHPh, OC4H9, OPh and SCH3, and examples of a group represented by E2 in formula (X-5b) include NH, NCH3, NC2H5, NPh, NHNC3H7 and NHNPh.
Examples of an alkyl group and an alkenyl group represented by each of R29, R30 and R31 in those formulae include substituted or unsubstituted, straight-chain or branched alkyl groups containing 1 to 10 carbon atoms (such as methyl, ethyl, isopropyl, n-propyl, n-butyl, t-butyl, 2-pentyl, n-hexyl, n-octyl, t-octyl, 2-ethylhexyl, hydroxymethyl, 2-hydroxyethyl, 1-hydroxyethyl, diethylaminoethyl, dibutylaminoethyl, n-butoxymethyl, n-butoxypropyl and methoxymethyl), substituted or unsubstituted cyclic alkyl groups containing 3 to 6 carbon atoms (such as cyclopropyl, cyclopentyl and cyclohexyl), and alkenyl groups containing 2 to 10 carbon atoms (such as allyl, 2-butenyl and 3-pentenyl). Examples of an aryl group represented by each of R29, R30 and R31 in those formulae include substituted or unsubstituted aryl groups containing 6 to 12 carbon atoms (such as unsubstituted phenyl and 4-methylphenyl), and those of a heterocyclic group include heterocyclic groups which each have no substituent or an alkyl, alkenyl, aryl or heterocyclic substitutent (such as pyridyl, 3-phenylpyridyl, furyl, piperidyl and morpholinyl).
Each of R29, R30 and R31 may further have a substituent Y.
Of the groups represented by formulae (X-5a) and (X-5b), the following are desirable.
In those formulae, it is desirable that E1 be an alkyl-substituted or unsubstiuted amino group or an alkoxy group, E2 be an alkyl-substitued or unsubstituted amino linkage, R29, R30 and R31 be each a substituted or unsubstituted alkyl group containing 1 to 6 carbon atoms or a substituted or unsubstituted aryl group containing 6 to 10 carbon atoms, and Z3 be S or Se.
Therein, it is more desirable that E1 be an alkyl-substituted or unsubstiuted amino group, E2 be an alkyl-substitued or unsubstituted amino linkage, R29, R30 and R31 be each a substituted or unsubstituted alkyl group containing 1 to 4 carbon atoms and Z3 be S.
Formulae (X-6a) and (X-6b) are illustrated below in detail.
Examples of a group represented by G2 and J each in formula (X-6b) include COOCH3, COOC3H7, COOC6H13, COOPh, SO2CH3, SO2C4H9, COC2H5, COPh, SOCH3, SOPh, CN, CHO and NO2.
Examples of a linkage group represented by R33 in formula (X-6a) incldue substituted or unsubstituted, straight-chain or branched alkylene groups containing 1 to 20 carbon atoms (such as methylene, ethylene, trimethylene, isopropylene, tetramethylene, hexamethylene, 3-oxapentylene and 2-hydroxytrimethylene), substituted or unsubstituted cycloalkylene groups containing 3 to 18 carbon atoms (such as cyclopropylene, cyclopentylene and cyclohexylene), substituted or unsubstituted alkenylene groups containing 2 to 20 carbon atoms (such as ethenylene and 2-butenylene), alkynylene groups containing 2 to 10 carbon atoms (such as ethynylene), and substituted or unsubstituted arylene groups containing 6 to 20 carbon atoms (such as unsubstituted p-phenylene and unsubstituted 2,5-naphthylene).
Examples of a heterocyclic group represented by R33 in formula (X-6a) include divalent heterocyclic groups having no substituent and alkylene-, alkenylene-, arylene- or hetero-cyclic group-substituted divalent heterocyclic groups (such as divalent groups derived from pyridine, 3-phenylpyridine, furan, piperidine and morpholine respectively).
Each of the groups represented by R33 may further have a substituent Y.
Of the groups represented by formulae (X-6a) and (X-6b) each, the following are desirable.
In these formulae, it is desirable that G2 and J be each an esterified carboxyl residue containing 2 to 6 carbon atoms or acyl group containing 1 to 6 carbon atoms, and R33 be a substituted or unsubstituted alkylene group containing 1 to 6 carbon atoms or a substituted or unsubstituted arylene group containing 6 to 10 carbon atoms.
Therein, it is more desirable that G2 and J be each an esterified carboxyl residue containing 2 to 4 carbon atoms and R33 be a substituted or unsubstituted alkylene group containing 1 to 4 carbon atoms or a substituted or unsubstituted arylene group containing 6 to 8 carbon atoms.
With respect to the ranking of silver halide adsorbing groups represented by X, the following is the descending order of suitability:
(X-1) greater than (X-2a) greater than (X-2b) greater than (X-3) greater than (X-5a) greater than (X-5b) greater than (X-4) greater than (X-6a) greater than (X-6b)
Next the light-absorbing group represented by X in formula (I) is illustrated in detail.
The light-absorbing group as X includes those represented by the following formula (X-7): 
wherein Z4 represents atoms completing a 5- or 6-membered nitrogen-containing hetero ring, L2, L3, L4 and L5 each represents a methine group, p1 represents 0 or 1, n1 represents an integer of from 0 to 3, M1 represents a counter ion for attaining the charge balance, and m2 represents the number of counter ions for neutralizing charges on the molecule and ranges from 0 to 10.
Examples of a 5- or 6-membered nitrogen-containing hetero ring completed by Z4 include thiazolidine, thiazole, benzothiazole, oxazoline, oxazole, benzoxazole, selenazoline, selenazole, benzoselenazole, 3,3-dialkylindolenine (such as 3,3-dimethylindolenine), imidazoline, imidazole, benzimidazole, 2-pyridine, 4-pyridine, 2-quinoline, 4-quinoline, 1-isoquinoline, 3-isoquinoline, imidazo[4,5-b]quinoxaline, oxadiazole, thiadiazole, tetrazole and pyrimidine nuclei.
The 5- or 6-membered nitrogen-containing hetero ring completed by Z4 may have the substituent Y as recited hereinbefore.
L2, L3, L4 and L5 in the foregoing formula are independent methine groups. The methine group represented by L2, L3, L4 and L5 each may have a substituent. Examples of such a substituent include substituted or unsubstituted alkyl groups containing 1 to 15 carbon atoms (such as methyl, ethyl and 2-carbooxyethyl), substituted or unsubstituted aryl groups containing 6 to 20 carbon atoms (such as phenyl and o-carboxyphenyl), substituted or unsubstituted heterocyclic group containing 3 to 20 carbon atoms (such as N,N-diethylbarbituric acid group), halogen atoms (such as chlorine, bromine, fluorine and iodine), alkoxy groups containing 1 to 15 carbon atoms (such as methoxy and ethoxy), alkylthio groups containing 1 to 15 carbon atoms (such as methylthio and ethylthio), arylthio groups containing 6 to 20 carbon atoms (such as phenylthio) and amino groups containing 0 to 15 carbon atoms (such as N,N-diphenylamino, N-methyl-N-phenylamino and N-methylpiperazine).
Each of the methine groups may combine with another methine group to form a ring. In addition, it is equally possible that each methine group combines with some other moiety to form a ring.
M1 is incorporated in formula (X-7) to indicate the presence of cation(s) or anion(s) required for neutralizing ionic charge on the light absorbing group. Examples of typical cation include hydrogen ion (H+), inorganic cations such as alkali metal ions (e.g., sodium, potassium and lithium ions), and organic cations such as ammonium ions (e.g., ammonium, tetraalkylammonium, pyridinium and ethylpyridinium ions). The anions also may be inorganic or organic ones, with examples including halogen anions (such as fluorine, chlorine and iodine ions), substituted arylsulfonic acid ions (such as p-toluenesulfonic acid ion and p-chlorobenzenesulfonic acid ion) aryldisulfonic acid ions (such as 1,3-benzenedisulfonic acid ion, 1,5-naphthalenedisulfonic acid ion and 2,6-naphthalenedisulfonic acid ion), alkylsulfate ions (such as methylsulfate ion), sulfuric acid ion, thiocyanic acid ion, perchloric acid ion, tetrafluoroboric acid ion, picric acid ion, acetic acid ion, and trifluoromethanesulfonic acid ion. Further, ionic polymers or other light absorbing groups bearing the opposite charge may be used as M1.
Herein, the sulfo group and the carboxyl group are shown, e.g., by SO3xe2x88x92 and CO2xe2x88x92, respectively. When the counter ion is hydrogen ion, however, these groups are represented by SO3H and CO2H respectively.
m2 is the number required for attaining the charge balance, and it is 0 when the inner salt is formed.
Of the light-absorbing groups represented by formula (X-7), the following are desirable.
In the above formula, it is desirable that Z4 be a benzoxazole, benzothiazole, benzimidazole or quinoline nucleus, L2, L3, L4 and L5 be each an unsubstituted methine group, P1 is 0 and n1 is 1 or 2.
Therein, it is more desirable that Z4 be a benzoxazole or benzothiazole nucleus and n1 is 1. In particular, the benzothiazole nucleus is preferred as Z4.
1 in formula (I) is preferably 0 or 1, more preferably 1.
Examples of the group X used in the invention are illustrated below, but these examples should not be construed as limiting the scope of the invention in any way. 
The linkage group represented by L in formula (I) is illustrated below.
Examples of such a linkage group include substituted or unsubstituted, straight-chain or branched alkylene groups containing 1 to 20 carbon atoms (such as methylene, ethylene, trimethylene, isopropylene, tetramethylene, hexamethylene, 3-oxapentylene and 2-hydroxytrimethylene), substituted or unsubstituted cycloalkylene groups containing 3 to 18 carbon atoms (such as cyclopropylene, cyclopentylene and cyclohexylene), substituted or unsubstituted alkenylene groups containing 2 to 20 carbon atoms (such as ethenylene and 2-butenylene), alkynylene groups containing 2 to 10 carbon atoms (such as ethynylene), substituted or unsubstituted arylene groups containing 6 to 20 carbon atoms (such as unsubstituted p-phenylene and unsubstituted 2,5-naphthylene), heterocyclic linkage groups (such as 2,6-pyridylene), a carbonyl group (xe2x80x94COxe2x80x94), a thiocarbonyl group (xe2x80x94CSxe2x80x94), an imido group (xe2x80x94NHxe2x80x94), a sulfonyl group (xe2x80x94SO2xe2x80x94), a sulfonate linkage (xe2x80x94SO2xe2x80x94Oxe2x80x94), an ester linkage (xe2x80x94COOxe2x80x94), a thoester linkage (xe2x80x94CSOxe2x80x94), an amido linkage (xe2x80x94CONHxe2x80x94), an ether linkage (xe2x80x94Oxe2x80x94), a thoether linkage (xe2x80x94Sxe2x80x94), an ureide linkage (xe2x80x94NHCONHxe2x80x94), a thioureide linkage (xe2x80x94NHCSNHxe2x80x94) and a thiosulfonyl group (xe2x80x94SO2xe2x80x94Sxe2x80x94). Two or more of these linkage groups may combine with each other to form a new linkage group.
L may further have the substituent Y as recited above.
It is desirable that the linkage group L be an unsubstituted alkylene group containing 1 to 10 carbon atoms or a group formed by linking xe2x80x94NHxe2x80x94, xe2x80x94CONHxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94NHCONHxe2x80x94 or xe2x80x94SO2xe2x80x94 with an alkylene group containing 1 to 10 carbon atoms, preferably an unsubstituted alkylene group containing 1 to 6 carbon atoms or a group formed by linking xe2x80x94NHxe2x80x94, xe2x80x94NHCOxe2x80x94 or xe2x80x94Sxe2x80x94 with an alkylene group containing 1 to 6 carbon atoms.
m in formula (I) is preferably 0 or 1, more preferably 1.
Then, the electron-donating group A is illustrated below.
The sensitivity increase can be attained with a reaction mechanism that the Axe2x80x94B moiety is oxidized and fragmentized to release an electron and produce radical B. and further the radical B. undergoes oxidation to produce an electron. This reaction mechanism is shown below: 
As A is an electron-donating group, it is desirable that the substituent(s) on an aromatic nucleus be selected so as to bring about an excessive state of electron in the group no matter what structure the nucleus has. More specifically, it is desirable that the oxidation potential be adjusted to the appropriate range by introducing into an aromatic nucleus, for example, electron-donating substituent(s) in a case where the nucleus is not in an excessive state of electron, or electron-attracting substituent(s) in a case where the nucleus is in a state of large excess electron, such as in a case of anthracene.
The groups suitable for the group A are those having the following formulae (A-1), (A-2) and (A-3) respectively: 
In formulae (A-1) and (A-2), R35 and R36 each represents a hydrogen atom, or a substituted or unsubstitued alkyl, aryl, alkylene or arylene group; R37 represents an alkyl group, COOH, halogen, N(R38)2, (OH)n, (OR38)n, (SR38)n, OR36, SR38, CHO, COR38, COOR38, CONHR38, CON(R38)2, SO3R38, SO2NHR38, SO2NR38, SO2R38, SOR38 or CSR38; and Ar1 represents an arylene group or a heterocyclic group. Herein, R35 and R36, or R35 and Ar1 may combine with each other to form a ring. Q2 represents O, S, Se or Te, m is 0 or 1, and n is 1 to 3. L2 represents Nxe2x80x94R, Nxe2x80x94Ar, O, S or Se. The form of the foregoing ring is a 5- to 7-membered heterocyclic ring or unsaturated hydrocarbon ring. R38 represents a hydrogen atom, an alkyl group or an aryl group.
The ring form of formula (A-3) is a substituted or unsubstitutted 5- to 7-membered unsaturated ring or heterocyclic ring.
Further, the formulae (A-1), (A-2) and (A-3) are illustrated in detail.
The alkyl group represented by R35 and R36 each in formulae (A-1) and (A-2) includes substituted or unsubstituted, straight-chain or branched alkyl groupd containing 1 to 10 carbon atoms (e.g., methyl, ethyl, isopropyl, n-propyl, n-butyl, t-butyl, 2-pentyl, n-hexyl, n-octyl, t-octyl, 2-ethylhexyl, 2-hydroxyethyl, 1-hydroxyethyl, diethylaminoethyl, dibutyl-aminoethyl, n-butoxymethyl, methoxymethyl) and substituted or unsubstituted cycloalkyl group containing 3 to 6 carbon atoms (e.g., cyclopropyl, cyclopentyl, cyclohexyl), and the aryl group represented thereby includes substituted or unsubstituted aryl groups containing 6 to 12 carbon atoms (e.g., unsubstituted phenyl, 2-methylphenyl).
The alkylene group represented by R35 and R36 each in those formulae includes substituted or unsubstituted, straight-chain or branched alkylene groups containing 1 to 10 carbon atoms (e.g., methylene, ethylene, trimethylene, tetramethylene, methoxyethylene), and the arylene group represented thereby includes substituted or unsubstituted arylene groups containing 6 to 12 carbon atoms (e.g., unsubstituted phenylene, 2-methylphenylene, naphthylene).
The group represented by R37 in formulae (A-1) and (A-2) includes alkyl groups (e.g., methyl, ethyl, isopropyl, n-propyl, n-butyl, 2-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, 2-hydroxyethyl, n-butoxymethyl), a carboxyl group, halogen atoms (e.g., fluorine, chlorine, bromine), OH, N(CH3)2, NPh2, OCH3, OPh, SCH3, SPh, CHO, COCH3, COPh, COOC4H5, COOCH3, CONHC2H5, CON(CH3)2, SO3CH3, SO3C3H7, SO2NHCH3, SO2N(CH3)2, SOCH3, CSPh and CSCH3.
Ar1 in formulae (A-1) and (A-2) includes substituted or unsubstituted arylene groups containing 6 to 12 carbon atoms (e.g., phenylene, 2-methylphenylene, naphthylene) and substituted or unsubstituted heterocyclic groups (e.g., groups derived from pyrydine, 3-phenylpyridine and morpholine).
L2 in formula (A-1) includes NH, NCH3, NC4H9, NC3H7(i), NPh, N(Phxe2x80x94CH3), O, S, Se and Te.
The ring formed in formula (A-3) includes unsaturated 5 to 7-membered rings and heterocyclic rings (e.g., furan, piperidine, morpholine).
R35, R36, R37, Ar1 and L2 in formulae (A-1) and (A-2), and the ring in formula (A-3) each may further have the substituent Y as recited hereinbefore.
Suitable examples of groups represented by formulae (A-1), (A-2) and (A-3) respectively are described below.
In formulae (A-1) and (A-2), it is desirable that R35 and R36 each be a substituted or unsubstituted alkyl group containing 1 to 6 carbon atoms, an alkylene group or a substituted or unsubstituted aryl group containing 6 to 10 carbon atoms, R37 be a substituted or unsubstituted alkyl group containing 1 to 6 carbon atoms, an amino group substituted by one or two of alkyl groups containing 1 to 4 carbon atoms, a carboxyl group, a halogen atom or an esterified carboxylic acid residue containing 2 to 4 carbon atoms, Ar1 be a substituted or unsubstituted arylene group containing 6 to 10 carbon atoms, Q2 be O, S or Se, m be 0 or 1, n be 1 to 3, and L2 be an unsubstituted imino group or 1-3C alkyl-substituted imino group.
In formula (A-3), it is desirable that the ring formed be a 5- to 7-membered hetero ring.
Moreover, it is preferable in formulae (A-1) and (A-2) that R35 and R36 each be a substituted or unsubstituted alkyl group containing 1 to 4 carbon atoms or an alkylene group, R37 be an unsubstituted alkyl group containing 1 to 4 carbon atoms or an amino group substituted by one or two of alkyl groups containing 1 to 4 carbon atoms, Ar1 be a substituted or unsubstituted arylene group containing 6 to 10 carbon atoms, Q2 be O or S, m is 0, n be 1, and L2 be an unsubstituted or 1-3C alkyl-substituted imino group.
In formula (A-3), the ring formed is preferably a 5- or 6-membered hetero ring.
The group X is bonded to the Ar1, R35 or R36 moiety of the group A.
Examples of the group A usable in the invention are illustrated below, but these examples should not be construed as limiting the scope of. the invention in any way. 
Then, the releasing group B is illustrated in detail.
The groups suitable for B are represented by the following formulae (B-1), (B-2) and (B-3) respectively. 
In formulae (B-2) and (B-3), W represents Si, Sn or Ge, R39 groups each represent an alkyl group, and Ar2 groups each represent an aryl group.
The group represented by formulae (B-2) and (B-3) each can be bonded to the adsorbing group X.
Then, formulae (B-2) and (B-3) are illustrated in detail.
The alkyl group represented by R39 includes substituted or unsubstituted, straight-chain or branched alkyl groups containing 1 to 6 carbon atoms (e.g., methyl, ethyl, isopropyl, n-propyl, n-butyl, t-butyl, 2-pentyl, n-hexyl, n-octyl, t-octyl, 2-ethylhexyl, 2-hydroxyethyl, 1-hydroxyethyl, n-butoxyethyl, methoxymethyl), and the aryl group represented by Ar2 includes substituted or unsubstituted aryl groups containing 6 to 12 carbon atoms (e.g., phenyl, 2-methylphenyl).
R39 and Ar2 in formulae (B-2) and (B-3) respectively may further have the substituent Y as recited hereinbefore.
In formulae (B-2) and (B-3), it is desirable that R39 be a substituted or unsubstituted alkyl group containing 1 to 4 carbon atoms, Ar2 be a substituted or unsubstituted aryl group containing 1 to 10 carbon atoms and W be Si or Sn.
Therein, it is more desirable that R39 be a substituted or unsubstituted alkyl group containing 1 to 3 carbon atoms, Ar2 be a substituted or unsubstituted aryl group containing 6 to 8 carbon atoms and W be Si.
Of the groups represented by formulae (B-1), (B-2) and (B-3), the most desirable ones are COOxe2x88x92 represented by formula (B-1) and Si(R39)3 in formula (B-2)
In formula (I), it is desirable for xe2x80x9cnxe2x80x9d to be 1.
Examples of a compound represented by Axe2x80x94B which can be used in the invention are illustrated below, but these examples should not be construed as limiting the scope of the invention in any way. 
Examples of counter ions required for attaining charge balance in the compounds as illustrated above include sodium ion, potassium ion, triethylammonium ion, diisopropylammonium ion, tetrabutylammonium ion and tetramethylguanidinium ion.
The oxidation potential of Axe2x80x94B (E1) is desirably from 0 to 1.5 V, preferably from 0 to 1.0 V, particularly preferably from 0.3 to 1.0 V.
The oxidation potential of the radical A. generated from the bond cleavage reaction (E2) is desirably from xe2x88x920.6 to xe2x88x922.5 V, preferably from xe2x88x920.9 to xe2x88x922.0 V, particularly preferably from xe2x88x920.9 to xe2x88x921.6 V.
The methods for measuring the foregoing oxidation potentials are described below.
E1 can be determined using cyclic voltammetry. More specifically, the electron doner A is dissolved in a solution containing acetonitrile and 0.1M water solution of lithium perchlorate in a ratio of 80/20 by volume %. A vitrified carbon disk is used as an operating electrode, a platinum wire is used as a counter electrode, and the saturated calomel electrode (SCE) is used as a reference electrode. The measurement is made at 25xc2x0 C. with a potential scanning speed of 0. 1 V/sec. And the oxidation potential vs. SCE at the peak potential of cyclic voltammetry wave is taken as E1. The E1 values of compounds represented by Axe2x80x94B are disclosed in EP-A-93731.
The oxidation potential measurements of radicals can be made using transient electrochemistry and pulse radiolysis. These are reported in J. Am. chem. Soc. , 110, 132 (1988), ibid., 96, 1287 (1974), and ibid., 96, 1295 (1974).
Examples of compounds represented by formula (I) are illustrated below. However, the compounds usable in the invention should not be construed as being limited to these examples. 
The compounds represented by formula (I) can be synthesized with ease by the use of the methods disclosed in U.S. Pat. Nos. 5,747,235 and 5,747,236, EP-A-786692, EP-A-893731, EP-A-893732 and WO99/05570, and those following these methods.
The suitable amount of a compound represented by formula (I) incorporated in an emulsion layer is from 1xc3x9710xe2x88x929 to 2xc3x9710xe2x88x922 mole/mole of silver, preferably from 1xc3x9710xe2x88x927 to 2xc3x9710xe2x88x923 mole/mole silver.
In the next place, compounds represented by formulae (II) to (VI) respectively are illustrated below.
Examples of alkyl, alkenyl and alkynyl groups represented by R1 and R2 each in formula (II) include substituted or unsubstituted straight-chain or branched alkyl groups containing 1 to 10 carbon atoms (such as methyl, ethyl, isopropyl, n-propyl, n-butyl, t-butyl, 2-pentyl, n-hexyl, n-octyl, t-octyl, 2-ethylhexyl, hydroxymethyl, 2-hydroxyethyl, 1-hydroxyethyl, diethylaminoethyl, dibutylaminoethyl, n-butoxypropyl and methoxymethyl), substituted or unsubstituted cycloalkyl groups containing 3 to 6 carbon atoms (such as cyclopropyl, cyclopentyl and cyclohexyl), alkenyl groups containing 2 to 10 carbon atoms (such as allyl, 2-butenyl and 3-pentenyl), alkynyl groups containing 2 to 10 carbon atoms (such as propargyl and 3-pentynyl), and aralkyl groups containing 7 to 12 carbon atoms (such as benzyl); and examples of an aryl group represented by R1 and R2 each include substituted or unsubstituted phenyl groups containing 6 to 12 carbon atoms (such as unsubstituted phenyl and 4-methylphenyl).
Examples of alkyl, alkenyl and alkynyl groups represented by R3 and R4 each in formula (II) include substituted or unsubstituted straight-chain or branched alkyl groups containing 1 to 10 carbon atoms (such as methyl, ethyl, isopropyl, n-propyl, n-butyl, t-butyl, 2-pentyl, n-hexyl, n-octyl, t-octyl, 2-ethylhexyl, 2-hydroxyethyl, diethylaminoethyl, dibutylaminoethyl, methoxyethyl and ethoxyethoxyethyl), substituted or unsubstituted cycloalkyl groups containing 3 to 6 carbon atoms (such as cyclopropyl, cyclopentyl and cyclohexyl), alkenyl groups containing 2 to 10 carbon atoms (such as allyl, 2-butenyl and 3-pentenyl), alkynyl groups containing 2 to 10 carbon atoms (such as propargyl and 3-pentynyl), and aralkyl groups containing 7 to 12 carbon atoms (such as benzyl); and examples of an aryl group represented by R3 and R4 each include substituted or unsubstituted phenyl groups containing 6 to 12 carbon atoms (such as unsubstituted phenyl and 4-methylphenyl), and substituted or unsubstituted naphthyl groups containing 10 to 16 carbon atoms (such as unsubstituted naphthyl).
Further, R1 or R2 may combine with R3 or R4 to complete a ring.
Examples of alkyl, alkenyl and alkynyl groups represented by R5 in formula (II) include substituted or unsubstituted straight-chain or branched alkyl groups containing 1 to 8 carbon atoms (such as methyl, ethyl, isopropyl, n-propyl, n-butyl, t-butyl, 2-pentyl, n-hexyl, n-octyl, t-octyl, 2-ethylhexyl, 2-hydroxyethyl and diethylaminoethyl), substituted or unsubstituted cycloalkyl groups containing 3 to 6 carbon atoms (such as cyclopropyl, cyclopentyl and cyclohexyl), alkenyl groups containing 2 to 10 carbon atoms (such as allyl, 2-butenyl and 3-pentenyl), alkynyl groups containing 2 to 10 carbon atoms (such as propargyl and 3-pentynyl), and aralkyl groups containing 7 to 12 carbon atoms (such as benzyl); examples of an aryl group represented by xe2x80x94R5 include substituted or unsubstituted phenyl groups containing 6 to 16 carbon atoms (such as unsubstituted phenyl, 4-methylphenyl, 4-(2-hydroxyethyl)phenyl, 4-sulfophenyl, 4-chlorophenyl, 4-trifluoromethylphenyl, 3-trifluoromethylphenyl, 4-carboxy-phenyl, 2,5-dimethylphenyl, 4-dimethylaminophenyl, 4-(3-carboxypropionylamino)phenyl, 4-methoxyphenyl, 2-methoxy-phenyl, 2,5-dimethoxyphenyl and 2,4,6-trimethylphenyl), and substituted or unsubstituted naphthyl groups containing 10 to 16 carbon atoms (such as unsubstituted naphthyl and 4-methylnaphthyl); and examples of a heterocyclic group represented by R5 include pyridyl, furyl, imidazolyl, piperidyl and morpholinyl groups.
Each of R1, R2, R3, R4 and R5 in formula (II) may further have the substituent Y as recited hereinbefore.
Of the compounds represented by formula (II), desirable ones are as follows: In formula (II), R1 and R2 are each a substituted or unsubstituted straight-chain or branched alkyl group containing 1 to 4 carbon atoms or a substituted or unsubstituted phenyl group containing 6 to 10 carbon atoms, R3 and R4 are each a hydrogen atom, a substituted or unsubstituted straight-chain or branched alkyl group containing 1 to 4 carbon atoms or a substituted or unsubstituted phenyl group containing 6 to 10 carbon atoms, R5 is a substituted or unsubstituted phenyl group containing 6 to 12 carbon atoms, and besides, the compounds fitting to the foregoing conditions have molecular weight of at most 350.
It is more desirable in formula (II) that R1 and R2 each be a substituted or unsubstituted straight-chain alkyl group containing 1 to 3 carbon atoms, R3 and R4 each be a hydrogen atom, R5 be a substituted or unsubstituted phenyl group containing 6 to 10 carbon atoms, and besides, the compounds fitting to these conditions have molecular weight of at most 300. Particularly, it is advantageous that the total number of carbon atoms contained in R1 to R5 be at most 11.
Examples of a compound represented by formula (II) are illustrated below, but the invention should not be construed as being limited by these examples. 
The compounds represented by formula (II) can be obtained with ease as commercially produced chemicals or compounds synthesized therefrom by the use of known methods. Also, the compounds represented by formula (II) can be easily synthesized using the methods as described in J. Chem. Soc., 408 (1954), U.S. Pat. No. 2,743,279 (1953) and U.S. Pat. No. 2,772,282 (1953), or the methods based thereon.
It is desirable that the compounds represented by formula (II) be added to a layer adjacent to or other than an emulsion layer by incorporating them in a coating composition for forming such a layer before or at the time when the coating composition is coated, and then allowed to be dispersed into the emulsion layer. However, they may be added to an emulsion during the emulsion-making, specifically before, during or after chemical sensitization. In other words, the compounds represented by formula (II) can be added to a light-sensitive layer as well as a light-insensitive layer.
The appropriate addition amount of those compounds, though it depends largely on the addition method adopted and the species of the compound(s) added, is generally from 5xc3x9710xe2x88x926 to 0.05 mole, preferably from 1xc3x9710xe2x88x925 to 0.005 mole, per mole of light-sensitive silver halide. When the amount added is greater than the foregoing upper limit, undesirable results, including an increase in fog, are produced.
In adding the compounds represented by formula (II), it is desirable that they be dissolved in a solvent soluble in water. The pH of their solutions may be lowered or heightened by adding thereto an acid or a base. On the other hand, the surfactants may be present therein. Those compounds may be dissolved in high boiling organic solvents and added as emulsified dispersions, or they may be made into microcrystalline dispersions according to known methods and then added.
The compounds represented by formula (III) are illustrated below in detail.
First the hydrazine structure represented by R6R7Nxe2x80x94NR8R9 suitable for Hy is described in detail.
R6, R7, R8 and R9 each represents an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group. Further, R6 and R7, R8 and R9, R6 and R8, or R7 and R9 may combine with each other to form a ring so far as the ring is not an aromatic hetero ring.
However, at least one among R6, R7, R8 and R9 is required to be an alkylene group, an alkenylene group, an alkynylene group, arylene group or a divalent heterocyclic reside for enabling Hy to link with the xe2x80x94(Q1)k2xe2x80x94(Het)k1 moiety in formula (III).
Examples of R6, R7, R8 and R9 each includes unsubstituted alkyl, alkenyl and alkynyl groups containing 1 to 18, preferably 1 to 8, carbon atoms (such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, hexyl, octyl, dodecyl, octadecyl, cyclopentyl, cyclopropyl and cyclohexyl), and substituted alkyl, alkenyl and alkynyl groups containing 1 to 18 carbon atoms, preferably 1 to 8 carbon atoms.
The ring formed by combining R6 with R7, R8 with R9, R6 with R8, or R7 with R9 may have the substituent Y as recited hereinbefore.
Suitable examples for R6, R7, R8 and R9 each includes unsubstituted alkyl, alkenyl and alkynyl groups, substituted alkyl, alkenyl and alkynyl groups, and an alkylene group, which may have a substituent (for example, the substituent Y as recited hereinbefore), in the case of forming a ring by R6 and R7, R8 and R9, R6 and R8, or R7 and R9 being combined with each other.
More suitable examples of a more desirable group for R6, R7, R8 and R9 each includes groups wherein the carbon atom attached to the nitrogen atom of hydrazine has the form of unsubstituted methylene. As particularly suitable examples for R6, R7, R8 and R9 each, mention may be made of unsubstituted alkyl groups containing 1 to 6 carbon atoms (such as methyl, ethyl, propyl and butyl), substituted alkyl groups containing 1 to 8 carbon atoms (e.g. , sulfoalkyl groups, such as 2-sulfoethyl, 3-sulfopropyl, 4-sulfobutyl and 3-sulfobutyl; carboxyalkyl groups, such as carboxymethyl and 2-carboxyethyl; hydroxyalkyl groups, such as 2-hydroxyethyl), and alkylene groups for forming 5- to 7-menbered rings in the case where R6 and R7, R8 and R9, R6 and R8, or R7 and R9 are combined with each other to complete those rings.
The hydrazine represented by R6R7Nxe2x80x94NR8R9 has at least one substituent represented by xe2x80x94(Q1)k2xe2x80x94(Het)k1. Such a substituent may be located in any of R6, R7, R8 and R9.
Further, the compounds represented by the following formulae (Hy-1), (Hy-2) and (Hy-3) respectively are desirable in particular for the compounds represented by R6R7Nxe2x80x94NR8R9 in the invention: 
wherein R39, R40, R41 and R42, which are independent of each other, each represents an alkyl group, an alkenyl group, alkynyl group, an aryl group or a heterocyclic group, or R39 and R40, or R41 and R42 combine with each other to complete a ring; Z4 represents an alkylene group containing 4, 5 or 6 carbon atoms; Z5 represents an alkylene group containing 2 carbon atoms; Z6 represents an alkylene group containing 1 or 2 carbon atoms; Z7 and Z8 each represents an alkylene group containing 3 carbon atoms; L3 and L4 each represents a methine group.
In formulae (Hy-1), (Hy-2) and (Hy-3) each, at least one substituent represented by xe2x80x94(Q1)k2xe2x80x94(Het)k1 is present.
The compounds selected from those represented by formulae (Hy-1) and (Hy-2) respectively are preferable, and the compounds selected from those represented by formula (Hy-1) are advantageous in particular.
The compounds represented by formula (Hy-1) are illustrated below.
R39 and R40 each in formula (Hy-1) have the same meaning as R6, R7, R8 and R9 each has, and the suitable ranges thereof are also the same.
In particularly preferable cases, R39 and R40 are each an alkyl group, or R39 and R40 combine with each other to form an unsubstituted tetramethylene or pentamethylene group.
Z4 represents an alkylene group containing 4, 5 or 6 carbon atoms, preferably an alkylene group containing 4 or 5 carbon atoms.
However, the carbon atom directly attached to the nitrogen atom of hydrazine has no oxo substituent.
The foregoing alkylene group may have no substituent or a certain substituent. This substituent includes the substituent Y recited hereinbefore. However, it is desirable that the carbon atom directly bonded to the nitrogen atom of hydrazine have the form of unsubstituted methylene.
It is particularly desirable for Z4 to be an unsubstituted tetramethylene or pentamethylene group.
The hydrazine represented by formula (Hy-1) has at least one substituent represented by xe2x80x94(Q1)k2xe2x80x94(Het)k1. This substituent may be located in any of R39, R40 and Z4, preferably R39 or R40.
Then, the compounds represented by formula (Hy-2) are described in detail.
R41 and R42 each have the same meaning as R6, R7, R8 and R9 each has, and the suitable ranges thereof are also the same.
In particularly preferable cases, R41 and R42 are each an alkyl group, or R41 and R42 combine with each other to form a trimethylene group.
Z5 represents an alkylene group containing 2 carbon atoms.
Z6 represents an alkylene group containing 1 or 2 carbon atoms.
These alkylene groups each may have no substituent or a certain substituent. This substituent includes the substituent Y as recited hereinbefore.
Preferably, Z5 is an unsubstituted ethylene group, and Z6 is an unsubstituted methylene or ethylene group.
L3 and L4 each represents a substituted or unsubstituted methine group. L3 and L4 each may have, e.g. , the substituent Y as recited hereinbefore, preferably an unsubstituted alkyl group (such as methyl or t-butyl). Preferably, L3 and L4 are each an unsubstituted methine group.
The hydrazine represented by formula (Hy-2) has at least one substituent represented by xe2x80x94(Q1)k2xe2x80x94(Het)k1. This substituent may be located in any of R41, R42, Z5, Z6, L3 and L4, preferably R41 or R42.
Further, the compounds represented by formula (Hy-3) are described in detail.
Z7 and Z8, which are independent of each other, each represents an alkylene group containing 3 carbon atoms.
However, the carbon atom directly attached to the nitrogen atom of hydrazine has no oxo substituent.
The foregoing alkylene group may have no substituent or a certain substituent. This substituent includes, e.g., the substituent Y as recited hereinbefore. However, it is desirable that the carbon atom directly attached to the nitrogen atom of hydrazine assume the form of unsubstituted methylene.
The alkylene group particularly preferred as Z7 and Z8 each is an unsubstituted trimethylene group or a substituted trimethylene group (such as 2,2-dimethyltrimethylene).
The hydrazine represented by formula (Hy-3) has at least one substituent represented by xe2x80x94(Q1)k2xe2x80x94(Het)k1. This substituent may be located in either Z7 or Z8.
The moiety represented by Het in formula (III) has any of the structures (1) to (5) described below:
(1) A 5-, 6- or 7-membered heterocyclic structure containing at least 2 hetero atoms,
(2) A 5-, 6- or 7-membered quaternary nitrogen-containing heterocyclic structure represented by the following formula A,
(3) A 5-, 6- or 7-membered nitrogen-containing heterocyclic structure which has a thioxo group and is represented by the following formula B,
(4) A 5-, 6- or 7-membered nitrogen-containing heterocyclic structure represented by the following formula C, and
(5) A 5-, 6- or 7-membered nitrogen-containing heterocyclic structure represented by the following formula D or E. 
In the above formulae, Zc represents atoms completing a 5-, 6- or 7-membered nitrogen-containing hetero ring, Ra represents an aliphatic group, La and Lb each represents a methine group, and n represents 0, 1 or 2.
Suitable examples of an aliphatic group represented by Ra include the groups recited above as examples of alkyl, alkenyl and alkynyl groups which R6, R7, R8 and R9 each represents.
The nitrogen-containing hetero ring in which Zc is comprised as a ring constituent is a 5-, 6- or 7-membered hetero ring which contains at least one nitrogen atom and may further contain another hetero atom (e.g., oxygen, sulfur, selenium, tellurium). Suitable examples of such a hetero ring include azole rings (such as imidazole, triazole, tetrazole, oxazole, thiazole, selenazole, benzimidazole, benzotriazole, benzoxazole, benzothiazole, thiadiazole, oxadiazole, benzoselenazole, pyrazole, naphthothiazole, naphthimidazole, naphthoxazole, azabenzimidazole and purine), a pyrimidine ring, a triazine ring, and azaindene rings (such as triazaindene, tetrazaindene and pentazaindene).
Additionally, the moiety represented by Het has at least one substituent represented by xe2x80x94(Q1)k2xe2x80x94(Hy).
The heterocyclic structures preferred as Het are those represented by the following formulae (Het-a), (Het-b), (Het-c), (Het-d) and (Het-e) respectively: 
In the above formulae, R43, R44, R45, R46, R47 and R48, which are independent of each other, each represents a hydrogen atom or a monovalent substituent.
R49 represents an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group.
X1 represents a hydrogen atom, an alkali metal atom, an ammonium group, or a blocking group.
Y1 represents an oxygen atom, a sulfur atom,  greater than NH, or  greater than Nxe2x80x94(L4)p3xe2x80x94R53, L3 and L4 each represents a linkage group, and R50 and R53 each represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group.
X2 has the same meaning as X1.
p2 and p3 each represents an integer of from 0 to 3, preferably 1.
Z9 represents atoms completing a 5- or 6-membered nitrogen-containing hetero ring.
R51 represents an alkyl group, an alkenyl group or an alkynyl group.
R52 represents a hydrogen atom, an alkyl group, an alkenyl group or an alkynyl group.
Additionally, each of the moieties represented by formulae (Het-a) to (Het-e) has at least one substituent represented by xe2x80x94(Q1)k2xe2x80x94(Hy). However, such a substituent is located neither in X1 of formula (Het-c) nor in X2 of formula (Het-d).
Of formulae (Het-a) to (Het-e), the formulae (Het-a), (Het-c) and (Het-d) are preferred over the others, and the formula (Het-c) is most advantageous.
Then, the formulae (Het-a) to (Het-e) are illustrated in further detail.
R43, R44, R45, R46, R47 and R48 each represents a hydrogen atom or a monovalent substituent. This monovalent substituent can include the groups which R6, R7, R8 and R9 each can represent, and those recited as the substituent Y.
Examples of a group preferred as the foregoing monovalent substituent include lower alkyl groups (preferably substituted or unsubstituted alkyl groups containing 1 to 4 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, t-butyl, methoxyethyl, hydroxyethyl, hydroxymethyl, vinyl and allyl), a carboxyl group, alkoxy groups (preferably substituted or unsubstituted alkoxy groups containing 1 to 5 carbon atoms, such as methoxy, ethoxy, methoxyethoxy and hydroxyethoxy), aralkyl groups (preferably substituted or unsubstituted aralkyl groups containing 7 to 12 carbon atoms, such as benzyl, phenetyl and phenylpropyl), aryl groups (preferably substituted or unsubstituted aryl groups containing 6 to 12 carbon atoms, such as phenyl, 4-methylphenyl and 4-methoxyphenyl), heterocyclic groups (such as 2-pyridyl), alkylthio groups (preferably substituted or unsubstituted alkylthio groups containing 1 to 10 carbon atoms, such as methylthio and ethylthio), arylthio groups (preferably substituted or unsubstituted arylthio groups containing 6 to 12 carbon atoms, such as phenylthio), aryloxy groups (preferably substituted or unsubstituted aryloxy groups containing 6 to 12 carbon atoms, such as phenoxy) alkylamino groups containing at least 3 carbon atoms (such as propylamino and butylamino), arylamino groups (such as anilino), halogen atoms (such as chlorine, bromine, fluorine), and the following substituents: 
wherein L5, L6 and L7 each represents an alkylene group as a linkage group (preferably those containing 1 to 5 carbon atoms, such as methylene, propylene and 2-hydroxypropylene); and R54 and R55, which may be the same or different, each represents a hydrogen atom, an alkyl, alkenyl or alkynyl group (preferably a 1-10C substituted or unsubstituted group, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, t-butyl, n-octyl, methoxyethyl, hydroxyethyl, allyl or propargyl), an aralkyl group (preferably a substituted or unsubstituted aralkyl group containing 7 to 12 carbon atoms, such as benzyl, phenetyl or vinylbenzyl), an aryl group (preferably a substituted or unsubstituted aryl group containing 6 to 12 carbon atoms, such as phenyl or 4-methylphenyl) or a heterocyclic group (such as 2-pyridyl).
The alkyl, alkenyl, alkynyl, aryl and heterocyclic groups which R49 can represent may have no substituent or a certain substituent. Examples of a substituent suitable for the group represented by R49 include the groups represented by R6, R7, R8 and R9, and the substituents recited as Y.
As examples of a more suitable substituent for the group represented by R49, mention may be made of a halogen atom (such as chlorine, bromine or fluorine), a nitro group, a cyano group, a hydroxyl group, an alkoxy group (such as methoxy), an aryl group (such as phenyl), an acylamino group (such as propionylamino), an alkoxycarbonylamino group (such as methoxycarbonylamino), an ureido group, an amino group, a heterocyclic group (such as 2-pyridyl), an acyl group (such as acetyl), a sulfamoyl group, a sulfonamido group, a thioureido group, a carbamoyl group, an alkylthio group (such as methylthio), an arylthio grouop (such as phenylthio), a heterocyclylthio group (such as 2-benzothiazolylthio), a carboxylic acid group, a carboxylate group, a sulfo group and a sulfonate group.
Each of the above-recited ureido, thioureido, sulfamoyl, carbamoyl and amino groups includes unsubstitued one, N-(alkyl-substituted) one and N-(aryl-substituted) one.
In the aryl group are included unsubstituted phenyl and substituted phenyl groups. The substituents which the phenyl group can have include the groups which R6, R7, R8 and R9 each can represent, and the groups recited as the substituent Y.
The alkali metal atom represented by X1 and X2 each is, e.g., sodium or potassium atom, and the ammonium group represented thereby is, e.g., tetramethylammonium or trimethylbenzylammonium. The blocking group represented by X1 and X2 each is a group capable of splitting off under an alkaline condition, such as acetyl, cyanoethyl or methanesulfonylethyl group.
Examples of a divalent linkage group represented by L3 and L4 each includes the following linkage groups and combinations of two or more of these groups: 
wherein R56, R57, R58, R59, R60, R61, R62, R63, R64 and R65, which are independent of each other, each represents a hydrogen atom, an alkyl, alkenyl or alkynyl group (preferably a substituted or unsubstituted 1-4C group, such as methyl, ethyl, n-butyl, methoxyethyl, hydroxyethyl or allyl), or an aralkyl group (preferably a substituted or unsubstituted 7-12C aralkyl group, such as benzyl, phenetyl or phenylpropyl).
The groups suitable for R50 and R53 each is similar to those recited above as examples of R49.
Suitable examples of a hetero ring having Z9 as a ring constituent include thiazoliums (such as thiazolium, 4-methylthiazolium, benzothiazolium, 5-methylbenzothiazolium, 5-chlorobenzothiazolium, 5-methoxybenzothiazolium, 6-methylbenzothiazolium, 6-methoxybenzothiazolium, naphtho-[1,2-d]thiazolium and naphtho[2,1-d]thiazolium), oxazoliums (such as oxazolium, 4-methyloxazolium, benzoxazolium, 5-chlorobenzoxazolium, 5-phenylbenzoxazolium, 5-methylblenzoxazolium or naphtho[l,2-d]oxazolium), imidazoliums (such as 1-methylbenzimidazolium, 1-propyl-5-chloro-benzimidazolium, 1-ethyl-5,6-cyclobenzimidazolium and 1-allyl-5-trifluoromethyl-6-chlorobenzimidazolium), and selenazoliums (such as benzoselenazolium, 5-chlorobenzoselenazolium, 5-methylbenzoselenazolium, 5-methoxybenzoselenazolium and naphtho[1,2-d]selenazolium).
Of these hetero rings, thiazoliums (such as benzothiazolium, 5-chlorobenzothiazolium, 5-methoxybenzothiazolium and naphtho[1,2-d]thiazolium) are preferred over the others.
Suitable examples of R51 and R52 each includes a hydrogen atom, unsubstituted 1-18C alkyl groups (such as methyl, ethyl, propyl, butyl, pentyl, octyl, decyl, dodecyl and octadecyl), substituted alkyl groups (which can have as a substituent, e.g , a vinyl group, a carboxyl group, a sulfo group, a cyano group or a halogen atom (such as fluorine, chlorine or bromine)), a hydroxyl group, 1-8C alkoxycarbonyl groups (such as methoxycarbonyl, ethoxycarbonyl, phenoxycarbonyl and benzyloxycarbonyl), 1-8C alkoxy groups (such as methoxy, ethoxy, benzyloxy and phenetyloxy), 6-10C monocyclic aryloxy groups (such as phenoxy and p-tollyloxy), 1-3C acyloxy groups (such as acetyloxy and propionyloxy), 1-8C acyl groups (such as acetyl, propionyl, benzoyl and mesyl), carbamoyl groups (such as carbamoyl, N,N-dimethylcarbamoyl, morpholinocarbonyl and piperidinocarbonyl), sulfamoyl groups (such as sulfamoyl, N,N-dimethylsulfamoyl, morpholinosulfonyl and piperidinosulfonyl) and 1-18C alkyl groups substituted by 6-10C aryl groups (such as phenyl, 4-chlorophenyl, 4-methylphenyl and xcex1-naphthyl). However, the case where R51 is a hydrogen atom is excluded therefrom.
Preferably, R51 is an unsubstituted alkyl group (such as methyl or ethyl) or an alkenyl group (such as allyl), and R52 is a hydrogen atom or an unsubstituted lower alkyl group (such as methyl or ethyl).
M1 and m1 are contained in formula (Het-e) in order to show whether the presence of cation or anion is required or not for neutralizing the ionic charge on the compound represented by formula (Het-e). Whether some dye bears a cation or an anion or no net ionic charge depends on its auxochrome and substituents. The typical cations are inorganic or organic ammonium ions and alkali metal ions, while the anions may be inorganic or organic ones. Examples of an anion usable for M1 include halide ions (such as fluoride, chloride, bromide and iodide ions), substituted arylsulfonate ions (such as p-toluenesulfonate ion and p-chlorobenzenesulfonate ion), aryldisulfonate ions (such as 1,3-benzenedisulfonate ion, 1,5-naphthalenedisulfonate ion and 2,6-naphthalenedisulfonate ion), alkylsulfate ions (such as methylsulfate ion), sulfate ion, thiocyanate ion, perchlorate ion, tetrafluoroborate ion, picrate ion, acetate ion and trifluoromethanesulfonate ion.
Of these cations and anions, ammonium ion, iodide ion, bromide ion and p-toluenesulfonate ion are preferred over the others.
Each of the nitrogen-containing hetero rings represented by formulae (Het-a) to (Het-e) has at least one substitutent represented by xe2x80x94(Q1)k2xe2x80x94(Hy). This substituent can be located in R43, R44, R45, R46, R47, R48, R49, R50, R51, Y1, L3 or Z9.
Q1 in formula (III) represents a divalent linkage group comprising at least one atom or atoms selected from among carbon, nitrogen, sulfur and oxygen atoms.
Preferably, Q1 represents a 1-8C alkylene group (such as methylene, ethylene, propylene, butylene or pentylene), a 6-12C arylene group (such as phenylene or naphthylene), a 2-8C alkenylene group (such as ethenylene or propenylene), an amide linkage, an ester linkage, a sulfamide linkage, a sulfonate linkage, an ureide linkage, a sulfonyl group, a sulfinyl group, a thioether linkage, an ether linkage, a carbonyl group, xe2x80x94N(R0)xe2x80x94 (wherein R0 is a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group), a divalent hetro ring residue (such as 6-chloro-1,3,5-triazizne-2,4-diyl, pyrimidine-2,4-diyl or quinoxaline-2,3-diyl), or a 4-20C divalent linkage group constituted of two or more of the above-recited ones. Of these linkage groups, ureide, ester and amide linkages are preferred over the others.
In formula (III), it is desirable that k1 and k3 be each 1 or 2. Preferably, all of k1, k2 and k3 are 1.
When k1 or k3 is at least 2, one Hy or Het may be the same as or different from another Hy or Het.
Of the present compounds represented by formula (III) the compounds represented by the following formulae (III-A), (III-B), (III-C), (III-D) and (III-E) respectively are preferable: 
In the invention, the compounds represented by the following formula (III-F) are preferred in particular: 
In the above formulae, Qa has the same meaning as Q1 in formula (III), Zd has the same meaning as Z4 in formula (Hy-1), R55 represents a monovalent substituent, R52 represents an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group, R53 and R54 each represents a hydrogen atom or a monovalent substituent, n1 represents an integer of from 0 to 4, n2 represents 0 or 1, n3 represents an integer of from 1 to 6, X1 has the same meaning as X1 in formula (Het-c), Y1 L3 and p3 have the same meanings as Y1, L3 and p3 in formula (Het-d) respectively, and R51 has the same meaning as R51 in formula (Het-e).
When n1 and n3 are each at least 2, it is not required for one R55 and one xe2x80x94C(R53) (R54)xe2x80x94 to be the same as another R55 and another xe2x80x94C(R53) (R54)xe2x80x94 respectively.
In more detail, the linkage groups suitable for Q1 in formula (III) are suitable for Qa also. In particular, it is advantageous that Qa be an ureide, ester or amide linkage.
The groups suitable for Zd are the same as those suitable for Z4 in formula (Hy-1), preferably unsubstituted tetramethylene and pentamethylene groups.
The groups suitable for R55 are the same as those suitable for R43.
The groups suitable for R52 are the same as those suitable for R6, R7, R8 and R9 each, particularly unsubstituted 1-4C alkyl groups (such as methyl and ethyl).
The groups suitable for R53 and R54 each are the same as those suitable for R43. In particular, hydrogen atom is preferred as R53 and R54 each.
n1 is preferably 0 or 1, n2 is preferably 1, and n3 is preferably 2 to 4.
Typical examples of the present compounds represented by formula (III) are illustrated below. However, these examples should not be construed as limiting the scope of the invention. 
The Het moiety in formula (III) usable in the invention includes those disclosed in U.S. Pat. No. 3,266,897, Belgian Patent 671,402, JP-A-60-138548, JP-A-59-68732, JP-A-59-123838, JP-B-58-9939, JP-A-59-137951, JP-A-57-202531, JP-A-57-164734, JP-A-57-14836, JP-A-57-116340, U.S. Pat. No. 4,418,140, JP-A-58-95728, JP-A-55-79436, West German Patent Application (OLS) 2,205,029, West German Patent Application (OLS) 1,962,605, JP-A-55-59463, JP-B-48-18257, JP-B-53-28084, JP-A-53-48723, JP-B-59-52414, JP-A-58-21798, JP-B-49-8334, U.S. Pat. Nos. 3,598,602, 887,009, U.K. Patent 965,047, Belgian Patent 737,809, U.S. Pat. No. 3,622,340, JP-A-60-87322, JP-A-57-211142, JP-A-58-158631, JP-A-59-15240, U.S. Pat. No. 3,671,255, JP-B-48-34166, JP-B-48-322112, JP-A-58-221839, JP-B-48-32367, JP-A-60-130731, JP-A-60-122936, JP-A-60-117240, U.S. Pat. No. 3,228,770, JP-B-43-13496, JP-B-43-10256, JP-B-47-8725, JP-B-47-30206, JP-B-47-4417, JP-B-51-25340, U.K. Patent 1,165,075, U.S. Pat. Nos. 3,512,982, 1,472,845, JP-B-39-22067, JP-B-39-22068, U.S. Pat. Nos. 3,148,067, 3,759,901, 3,909,268, JP-B-50-40665, JP-B-39-2829, U.S. Pat. No. 3,148,066, JP-B-45-22190, U.S. Pat. No. 1,399,449, U.K. Patent 1,287,284, U.S. Pat. No. 3,900,321, 3,655,391, 3,910,792, U.K. Patent 1,064,805, U.S. Pat. Nos. 3,544,336, 4,003,746, U.K. Patent 1,344,525, U.K. Patent 972,211, JP-B-43-4136, U.S. Pat. No. 3,140,178, French Patent 2,015,456, U.S. Pat. No. 3,114,637, Belgian Patent 681,359, U.S Pat. No. 3,220,839, U.K. Patent 1,290,868, U.S Pat. Nos. 3,137,578, 3,420,670, 2,759,908, 3,622,340, West German Patent Application (OLS) 2,501,261, West German Patent (DT-AS) 1,772,424, U.S. Pat. No. 3,157,509, French Patent 1,351,234, U.S. Pat. No. 3,630,745, French Patent 2,005,204, German Patent 1,447,796, U.S. Pat. No. 3,915,710, JP-B-49-8334, U.K. Patent 1,021,199, U.K. Patent 919,061, JP-B-46-17513, U.S. Pat. No. 3,202,512, West German Patent Application (OLS) 2,553,127, JP-A-50-104927, French Patent 1,467,510, U.S. Pat. Nos. 3,449,126, 3,503,936, 3,576,638, French Patent 2,093,209, U.K. Patent 1,246,311, U.S. Pat. Nos. 3,844,788, 3,535,115, U.K. Patent 1,161,264, U.S. Pat. Nos. 3,841,878, 3,615,616, JP-A-48-39039, U.K. Patent 1,249,077, JP-B-48-34166, U.S. Pat. No. 3,671,255, U.K. Patent 1,459,160, JP-A-50-6323, U.K. Patent 1,402,819, West German Patent Application (OLS) 2,031,314, Research Disclosure, No. 13651, U.S. Pat. Nos. 3,910,791, 3,954,478, 3,813,249, U.K. Patent 1,387,654, JP-A-57-135945, JP-A-57-96331, JP-A-57-22234, JP-A-59-26731, West German Patent Application (OLS) 2,217,153, U.K. Patent 1,394,371, U.K. Patent 1,308,777, U.K. Patent 1,389,089, U.K. Patent 1,347,544, German Patent 1,107,508, U.S. Pat. No. 3,386,831, U.K. Patent 1,129,623, JP-A-49-14120, JP-B-46-34675, JP-A-50-43923, U.S. Pat. No. 3,642,481, U.K. Patent 1,269,268, U.S. Pat. Nos. 3,128,185, 3,295,981, 3,396,023, 2,895,827, JP-B-48-38418, JP-A-48-47335, JP-A-50-87028, U.S. Pat. Nos. 3,236,652, 3,443,951, U.K. Patent 1,065,669, U.S. Pat. Nos. 3,312,552, 3,310,405, 3,300,312, U.K. Patent 952,162, U.K. Patent 948,442, JP-A-49-120628, JP-B-48-35372, JP-B-47-5315, JP-A-39-18706, JP-A-43-4941 and JP-A-59-34530. The Het moiety according to the invention can be synthesized by reference to the literature cited above.
The Hy moiety in formula (III) usable in the invention can be synthesized using various methods. For instance, it can be synthesized by the method of alkylating hydrazine. As to the alkylation method, there are known the method of alkylating hydrazine by substitution with a halogenated alkane and alkyl sulfonate, the reductive alkylation method using a carbonyl compound and a sodium cyanoborohydride, and the method of acylating hydrazine and then reducing the acylated hydrazine by the use of lithium aluminum hydride. These methods are described in S. R. Sandler and W. Karo, Organic Functional Group Preparation, vol. 1, chap. 14, pp. 434-465, Academic Press (1968), and E. L. Clennan et al., Journal of The American Chemical Society, vol. 112, No. 13, p. 5080 (1990). The desired compounds can be synthesized by reference to the literature cited above.
The linkage-forming reaction in the xe2x80x94(Q1)k2xe2x80x94(Hy) moiety, including the amide linkage- and ester linkage-forming reactions, can be effected utilizing the methods well known in organic chemistry. More specifically, the linkage formation can be carried out using a method properly selected from known methods, including the method of linking Het and Hy together, the method of linking Hy to a starting material and an intermediate of Het synthesis and then synthesizing the Het, and the method of linking a starting material and an intermediate of Hy synthesis to the Het moiety and then synthesizing Hy. For details of the synthesis reaction for the foregoing linkage formation, many books on organic synthesis reactions, e.g., Shin Jikken Kagaku Koza 14 (New Lectures on Experimental Chemistry, vol. 14, entitled xe2x80x9cSyntheses and Reactions of Organic Compoundsxe2x80x9d), Nos. I-V, compiled by Japanese Chemical Society, published by Maruzen, Tokyo (1977), Yoshiro Ogata, Yuki Hannoron (Theory of Organic Reactions), Maruzen, Tokyo (1962), and L. F. Fieser and M. Fieser, Advanced Organic Chemistry, Maruzen, Tokyo (1962), can be referred to.
More concretely, the linkage can be formed using the method described in Examples 1 and 2 of JP-A-7-135341.
When the compounds represented by formula (III) are added during the process of making emulsions, the addition may be carried out at any stage of the process. For instance, these compounds can be added to emulsions at the stage of forming silver halide grains, before the desalting stage begins, at the desalting stage, before the chemical ripening starts, at the chemical ripening stage, or before the finished emulsion is prepared. Additionally, the addition of the compound(s) may be portioned out to some different stages.
In adding the present compounds represented by formula (III), it is desirable for them to be dissolved in water, a water-soluble solvent, such as methanol or ethanol, or a mixture of these solvents. In a case where those compounds are dissolved in water and their solubilities in water can be raised by heightening or lowering the pH, it is favorable to dissolve them in the water adjusted to a high or low pH value respectively and add the resulting solution.
It is desirable to use the compounds represented by formula (III) in an emulsion layer. While the compounds may be added directly to the emulsion layer, they may be added to a coating solution for a protective layer or an interlayer and dispersed into the emulsion layer at the time the coating solution is applied.
It does not matter whether the compounds represented by formula (III) are added before or after sensitizing dyes are added. Their suitable content in a silver halide emulsion layer is from 1xc3x9710xe2x88x929 to 5xc3x9710xe2x88x922 mole, preferably from 1xc3x9710xe2x88x928 to 2xc3x9710xe2x88x923 mole, per mole of silver halide.
Then, the compounds represented by formulae (IV-1) and (IV-2) respectively are illustrated in detail.
Examples of a substituent represented by R10, R11, R12 and R13 each in formula (IV-1) include alkyl groups (containing preferably 1 to 30, particularly preferably 1 to 20, carbon atoms, such as methyl, ethyl and isopropyl), aralkyl groups (containing preferably 7 to 30, particularly preferably 7 to 20, carbon atoms, such as phenylmethyl), alkenyl groups (containing preferably 2 to 20, particularly preferably 2 to 10, carbon atoms, such as allyl), alkoxy groups (containing preferably 1 to 20, particularly preferably 1 to 10, carbon atoms, such as methoxy and ethoxy), aryl groups (containing preferably 6 to 30, particularly preferably 6 to 20, carbon atoms), acylamino groups (containing preferably 2 to 30, particularly preferably 2 to 20, carbon atoms, such as acetylamino), sulfonylamino groups (containing preferably 1 to 30, particularly preferably 1 to 20, carbon atoms, such as methanesulfonylamino), ureido groups (containing preferably 1 to 30, particularly preferably 1 to 20, carbon atoms, such as methylureido), alkoxycarbonylamino groups (containing preferably 2 to 30, particularly preferably 2 to 20, carbon atoms, such as methoxycarbonylamino), aryloxycarbonylamino groups (containing preferably 7 to 30, particularly preferably 7 to 20, carbon atoms, such as phenyloxycarbonylamino), aryloxy groups (containing preferably 6 to 30, particularly preferably 6 to 20, carbon atoms, such as phenyloxy), sulfamoyl groups (containing preferably 0 to 30, particularly preferably 0 to 20, carbon atoms, such as methylsulfamoyl), carbamoyl groups (containing preferably 1 to 30, particularly preferably 1 to 20, carbon atoms, such as carbamoyl and methylcarbamoyl), a mercapto group, alkylthio groups (containing preferably 1 to 30, particularly preferably 1 to 20, carbon atoms, such as methylthio and carboxymethylthio), arylthio groups (containing preferably 6 to 30, particularly preferably 6 to 20, carbon atoms, such as phenylthio), sulfonyl groups (containing preferably 1 to 30, particularly preferably 1 to 20, carbon atoms, such as methanesulfonyl), sulfinyl groups (containing preferably 1 to 30, particularly preferably 1 to 20, carbon atoms, such as methanesulfonyl), a hydroxyl group, halogen atoms (such as chlorine, bromine and fluorine atoms), a cyano group, a sulfo group, a carboxyl group, a phosphono group, amino groups (containing preferably 0 to 30, particularly preferably 1 to 20, carbon atoms, such as methylamino), aryloxycarbonyl groups (containing preferably 7 to 30, particularly preferably 7 to 20, carbon atoms), acyl groups (containing preferably 2 to 30, particularly preferably 2 to 20, carbon atoms, such as acetyl and benzoyl), alkoxycarbonyl groups (containing preferably 2 to 30, particularly preferably 2 to 20, carbon atoms, such as methoxycarbonyl), acyloxy groups (containing preferably2 to 30, particularly preferably 2 to 20, carbon atoms, such as acetoxy), a nitro group, a hydroxamic acid group, and heterocyclic groups (such as pyridyl, furyl and thienyl). Additionally, these substituents may further be substituted.
As suitable examples of a substituent represented by R10, R11, R12 and R13 each, mention may be made of an alkyl group, an alkoxy group, a hydroxyl group, a halogen atom, a sulfo group, a carboxyl group, an acylamino group, a sulfonylamino group, an ureido group, an alkoxycarbonylamino group, an aryloxycarbonylamino group, an alkylthio group, an arylthio group, an amino group and an acyloxy group. Preferably, they each represents an alkyl group, an alkoxy group, a halogen atom, a sulfo group, a carboxyl group, an acylamino group, a sulfonylamino group, an ureido group, an alkoxycarbonylamino group or an aryloxycarbonylamino group. In particular, it is advantageous for them each to be an alkyl group, a halogen atom, an acylamino group, a sulfonylamino group, an ureido group, an alkoxycarbonylamino group or an aryloxycarbonylamino group.
It is desirable for R10, R11, R12 and R13 that one to three among them be each a hydrogen atom. Preferably, two or three among them are each a hydrogen atom. In particular, it is advantageous that three among them be each a hydrogen atom.
When both R10 and R13 are alkyl groups, these alkyl groups are required to differ in the number of carbon atoms. For instance, it is an allowable case that R10 is txe2x80x94C8H17 and R13 is nxe2x80x94C15H31, but the case that both R10 and R13 are, e.g., txe2x80x94C8H17 is excluded. When R10 and R13 are substituents of the same type, the carbon number difference between them is preferably at least 5, particularly preferably at least 10. These restrictions imposed on the relation between R10 and R13 apply also to the relation between R11 and R12.
Of the compounds represented by formula (IV-1), the compounds represented by the following formula (IV-1-a) are desirable, those represented by the following formula (IV-1-b) are more desirable, and those represented by the following formula (IV-1-c) are most desirable. 
R31 and R34 in the above formula have the same meanings as R10 and R13 in formula (IV-1) respectively, and the desirable range of them is the same as that of R10 and R13. 
R31 in the above formula have the same meaning as R10 in formula (IV-1), and the desirable range thereof is the same as that of R10. 
R56 in the above formula is an unsubstituted or substituted alkyl group. To substituent(s) of this alkyl group can be applied those recited as examples of a substituent represented by R10.
As examples of a substituent represented by R14, R15 and R16 each in formula (IV-2), mention may be made of the substituents which the substituent represented by R10, R11, R12 and R13 each may have.
Suitable examples of a substituent represented by R14 include an alkyl group, an alkoxy group, a hydroxyl group, a halogen atom, a sulfo group, a carboxyl group, an acylamino group, a sulfonylamino group, an ureido group, an alkoxycarbonylamino group, an aryloxycarbonylamino group, an alkylthio group, an arylthio group, an amino group and an acyloxy group. Preferably, R14 represents an alkyl group, an alkoxy group, a halogen atom, a sulfo group, a carboxyl group, an acylamino group, a sulfonylamino group, an ureido group, an alkoxycarbonylamino group or an aryloxycarbonylamino group. In particular, it is advantageous for R14 to be an alkyl group, a halogen atom, an acylamino group, a sulfonylamino group, an ureido group, an alkoxycarbonylamino group or an aryloxycarbonylamino group.
Suitable examples of a substituent represented by R15 include an alkyl group, an alkoxy group, a hydroxyl group, a halogen atom, an acylamino group, a sulfonylamino group, an ureido group, an alkoxycarbonylamino group, an aryloxycarbonylamino group, an alkylthio group, an arylthio group, an amino group and an acyloxy group. Preferably, R15 represents an alkyl group, an alkoxy group, a hydroxyl group, an acylamino group, a sulfonylamino group, an ureido group, an alkoxycarbonylamino group or an aryloxycarbonylamino group. In particular, it is advantageous for R15 to be an alkyl group, an acylamino group, a sulfonylamino group, an ureido group, an alkoxycarbonylamino group or an aryloxycarbonylamino group.
Suitable examples of a substituent represented by R16 include an alkyl group, an alkoxy group, a hydroxyl group, a halogen atom, a sulfo group, a carboxyl group, an acylamino group, a sulfonylamino group, an ureido group, an alkoxycarbonylamino group, an aryloxycarbonylamino group, an alkylthio group, an arylthio group, an amino group and an acyloxy group. Preferably, R16 represents an alkyl group, an alkoxy group, a halogen atom, a sulfo group, a carboxyl group, an acylamino group, a sulfonylamino group, an ureido group, an alkoxycarbonylamino group or an aryloxycarbonylamino group. In particular, it is advantageous for R16 to be an alkyl group.
Z represents nonmetal atoms completing a 4- to 6-membered ring. Suitable examples of nonmetal atoms include carbon, oxygen, nitrogen and sulfur atoms. It is desirable that the nonmetal atoms include carbon and oxygen atoms. In particular, carbon atoms are preferred as the nonmetal atoms. The number of ring members is preferably 5 or 6, particularly preferably 6. These rings each may have one or more of a substituent thereon. To such a substituent can be applied, e.g., those recited as examples of a substituent represented by R14. Suitable examples of a substituent on the ring include an alkyl group, an alkenyl group and an alkoxy group. Of these groups, the alkyl group and the alkenyl group are preferred to the alkoxy group. These substituents may further be substituted.
Of the compounds represented by formula (IV-2), the preferable compounds are those represented by the following formula (IV-2-a), and the particularly preferable compounds are those represented by the following formula (IV-2-b). 
R14, R15 and R16 in the above formula have the same meanings as those in formula (IV-2) respectively, and the desirable ranges thereof are the same as those in formula (IV-2) respectively. n represents 1 or 2. R57 and R58 each represents an alkyl group, an alkenyl group or an alkoxy group. 
R14, R15and R16 in the above formula have the same meanings as those in formula (IV-2) respectively, and the desirable ranges thereof are the same as those in formula (IV-2) respectively. R57 represents an alkyl group, an alkenyl group or an alkoxy group. n is preferably 2.
The alkyl group and the alkenyl group which R57 and R58 each can represent may have any of straight-chain, branched and cyclic forms, preferably a straight-chain or branched form. The suitable number of carbon atoms contained therein is from 1 to 30, preferably from 1 to 20. Methyl, ethyl and isopropyl groups are examples of such an alkyl group, and allyl group is an example of such an alkenyl group.
The alkyl moiety of the alkoxy group represented by R57 and R58 each may have any of straight-chain, branched and cyclic forms, and R57 and R58 may combine with each other to form a ring, such as spirochromans. The suitable number of carbon atoms in the alkoxy group is from 1 to 20, preferably from 1 to 10. The alkoxy group represented by R57 and R58 each is, e.g., a methoxy or ethoxy group.
Examples of compounds represented by formulae (IV-1) and (IV-2) respectively are illustrated below, but these examples should not be construed as limiting the scope of the invention. 
The compounds represented by formula (IV) can be synthesized using the methods described, e.g., in U.S. Pat. Nos. 2,728,659, 2,549,118 and 2,732,300, Journal of American Chemical Society, vol. 111, No. 20, p. 7932 (1989), Synthesis, vol. 12, p. 1549 (1995), Q. J. Pharm. Pharmacol., vol. 17, p. 325 (1944), Chem. Pharm. Bull., vol. 14, p. 1052 (1966), and Chem. Pharm. Bull., vol. 16, p. 853 (1968).
In addition, the compounds represented by formula (IV) can also be synthesized using the methods disclosed, e.g., in U.S. Pat. Nos. 2,421,811, 2,421,812, 2,411,967 and 2,681,371, J. Amer. Chem. Soc., 65, 1943, 1276, J. Amer. Chem. Soc., 65, 1943, 1281, J. Amer. Chem. Soc., 63, 1941, 1887, J. Amer. Chem. Soc., 107, 24, 1985, 7053, Helv. Chim. Acta., 21, 1938, 939, Helv. Chim. Acta., 28, 1945, 436, Chem. Ber. 71, 1938, 2637, J. Or. Chem., 4, 1939, 311, J. Or. Chem., 6, 1941, 229, J. Chem. Soc., 1938,1382, Helv. Chim. Acta., 21 1931,1234, Tetrahedron Lett., 33, 26, 1992, 3795, J. chem. Soc. Perkin. Trans., 1, 1981, 1437, and Synthesis, 6, 1995, 693.
It is desirable that the present compounds represented by formulae (IV-1) and (IV-2) each be dispersedin an emulsified condition by the use of a known dispersion method and then added. At the time they are dispersed in an emulsified condition, the additives generally used in the photographic art, such as dye-forming couplers and high boiling organic solvents, can be present together with them. In addition, they can also be added as a microcrystalline dispersion.
The present compounds represented by formulae (IV-1) and (IV-2) each are added to an emulsion layer in an amount of 5xc3x9710xe2x88x924 to 1 mole, preferably 1xc3x9710xe2x88x923 to 5xc3x9710xe2x88x921 mole, per mole of silver halide in the emulsion layer.
As to the combinations of the compounds of formula (III) with the compounds of formula (IV-1) or (IV-2), the combinations of the compounds of formula (III-F) with the compounds of formula (IV-1-b) or (IV-2-b) are preferred over the others.
Further, the compounds represented by formulae (V-1) to (V-3) respectively are illustrated in more detail.
The term xe2x80x9calkyl groupxe2x80x9d as used herein is intended to include straight-chain, branched and cyclic alkyl groups, and further these alkyl groups may be substituted.
Ra1 in formula (V-1) represents an alkyl group (preferably a 1-13C alkyl group, such as methyl, ethyl, isopropyl, cyclopropyl, butyl, isobutyl, cyclohexyl, t-octyl, decyl, dodecyl, hexadecyl or benzyl), an alkenyl group (preferably a 2-14C alkenyl group, such as allyl, 2-butenyl, isopropenyl, oleyl or vinyl) or an aryl group (preferably a 6-14C aryl group, such as phenyl or naphthyl) Ra2 represents a hydrogen atom or a group represented by Ra1. Ra3 represents a hydrogen atom, a substituted or unsubstituted 1-10C alkyl group (such as methyl, isobutyl or cyclohexyl) or an alkenyl group (such as vinyl or isopropenyl). The total number of carbon atoms contained in Ra1, Ra2 and Ra3 is at most 20, preferably at most 12. As examples of a substituent which Ra1 to Ra3 can have, mention may be made of a hydroxyl group, an alkoxy group, an aryloxy group, a silyl group, a silyloxy group, an alkylthio group, an arylthio group, an amino group, an acylamino group, a sulfonamido group, an alkylamino group, an arylamino group, a carbamoyl group, a sulfamoyl group, a sulfo group, a carboxyl group, a halogen atom, a cyano group, a nitro group, a sulfonyl group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an acyloxy group, a hydroxyamino group and a heterocyclic group.
Ra1 and Ra3, or Ra2 and Ra3 may combine with each other to form a 5- to 7-membered ring.
Xa in formula (V-2) represents a heterocyclic group. More specifically, the heterocyclic group is a monovalent group derived from a 5- to 7-membered hetero ring containing at least one nitrogen, sulfur, oxygen or phosphorus atom as a ring-constituting hetero atom, and one of the carbon atoms constituting the ring provides the site for bonding. Examples of such a heterocyclic group include pyridine-2-yl, pyrazinyl, pyrimidinyl, purinyl, quinolyl, imidazolyl, thiazolyl, oxazolyl, 1,2,4-triazole-3-yl, benzimidazole-2-yl, benzothiazolyl, benzoxazolyl, thienyl, furyl, imidazolidinyl, pyrrolinyl, tetrahydrofuryl, 1,3,5-triazine-2-yl, 1,2,4-triazine-3-yl, morpholinyl and phosphinoline-2-yl. Rb1 represents an alkyl, alkenyl or aryl group. These groups have the same meanings as those represented by Ra1 in formula (V-1) respectively.
Y in formula (V-3) represents nonmetal atoms completing a 5-membered ring together with the xe2x80x94Nxe2x95x90Cxe2x80x94 moiety. The group derived from the 5-membered ring formed therein is, e.g., an imidazolyl group, a benzimidazolyl group, a 1,3-thiazole-2-yl group, a 2-imidazoline-2-yl group, a purinyl group or a 3H-indole-2-yl group. Further, Y is constituted of nonmetal atoms completing a 6-membered ring together with the xe2x80x94Nxe2x95x90Cxe2x80x94 moiety, and represents a divalent group whose end attached to the carbon atom of the xe2x80x94Nxe2x95x90Cxe2x80x94 moiety is xe2x80x94N(Rc1)xe2x80x94, xe2x80x94C(Rc2) (Rc3)xe2x80x94, xe2x80x94C(Rc4)xe2x95x90, xe2x80x94Oxe2x80x94 or xe2x80x94Sxe2x80x94 (which each is attached to the carbon atom of the xe2x80x94Nxe2x95x90Cxe2x80x94 moiety on the left side). Rc1 to Rc4, which may be the same or different, each represents a hydrogen atom or a substituent (such as an alkyl group, an alkenyl group, an aryl group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, an alkylamino group, an arylamino group, or a halogen atom). Examples of a 6-membered heterocyclic group represented by Y include quinolyl, isoquinolyl, phthalzinyl, quinoxalinyl, 1,3,5-triazine-5-yl and 6H-1,2,5-thiadiazine-6-yl.
In formula (V-2), it is desirable for Rb1 to be an alkyl group or an alkenyl group, especially an alkyl group.
Of the compounds represented by formula (V-2), the compounds represented by the following formula (V-4) are preferred over the others: 
wherein Rb1 has the same meaning as Rb1 in formula (V-2), and X1 has the same meaning as Y in formula (V-3).
The total number of carbon atoms contained in each of the compounds represented by formulae (V-1) to (V-3) is preferably at most 20, particularly preferably at most 12.
Of the compounds represented by formulae (V-1) to (V-3), those represented by formula (V-1) or (V-2) respectively are preferable to those represented by formula (V-3). And the compounds represented by formula (V-1) or (V-4) respectively are much preferable. In particular, the compounds represented by formula (V-1) are advantageous over the others.
Examples of compounds represented by formulae (V-1) to (V-3) respectively are illustrated below, but these examples should not be construes as limiting the scope of the invention. 
These compounds used in the invention can be easily synthesized using the methods described, e.g., in J. Org Chem., 27, 4054 (1962), J. Amer. Chem. Soc., 73, 2981 (1951) and JP-B-49-10692, or the methods following them.
The present compounds represented by formulae (V-1) to (V-3) may be added as a solution dissolved in water, a water-soluble solvent, such as methanol or ethanol, or a mixture of these solvents, or as an emulsified dispersion. In a case where those compounds are dissolved in water and their solubilities in water can be raised by heightening or lowering the pH, it is favorable to dissolve them in the water adjusted to a high or low pH value respectively and add the resulting solution. On the other hand, those compounds may be dissolved in the presence of a surfactant.
In the invention, it is desirable to add the compounds represented by formulae (V-I) to (V-3) during the process of making emulsions. In this case, the addition may be carried out at any stage of the process. For instance, these compounds can be added to emulsions at the stage of forming silver halide grains, before the desalting stage begins, at the desalting stage, before the chemical ripening starts, at the chemical ripening stage, or before the finished emulsion is prepared. Additionally, the addition of the compound(s) may be portioned out to some different stages. Preferably, those compounds are added before, during or after chemical sensitization. In another way, although the compounds can be added to a coating solution for the emulsion layer, the compounds can be added to a coating solution for a layer adjacent to the emulsion layer or another layer, and thereby dispersed into the emulsion layer at the time the coating solution is applied. In still another way, the emulsified dispersion(s) of those compounds may be mixed with a finished emulsion and then coated in a layer.
The suitable addition amount of the compounds represented by formulae (V-1) to (V-3), though it depends greatly on the addition method adopted and the species of the compounds added, is from 1xc3x9710xe2x88x926 to 5xc3x9710xe2x88x922 mole, preferably from 1xc3x9710xe2x88x925 to 5xc3x9710xe2x88x923 mole, per mole of light-sensitive silver halide.
In the invention, the compound represented by formula (III), the compound selected from those represented by formulae (IV-1) and (IV-2) and the compound selected from those represented by formulae (V-1) to (V-3) can be added to the same layer, or they may be added separate layers respectively.
Further, the compounds represented by formula (VI) are illustrated in detail.
In formula (VI), R17, R18 and R19, which are independent of each other, each represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group. R20 represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a heterocyclic group or NR59R60. L represents xe2x80x94COxe2x80x94 or xe2x80x94SO2xe2x80x94, and n represents 0 or 1. R59 represents a hydrogen atom, a hydroxyl group, an amino group, an alkyl group, an alkenyl group, an alkynyl group , an aryl group or a heterocyclic group, and R60 represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group.
As to the alkyl, alkenyl and alkynyl groups which R17, R18 and R19 each can represent, those containing 1 to 30 carbon atoms are desirable. Particularly preferred ones are 1-10C straight-chain, branched or cyclic alkyl groups, 2-10C alkenyl groups and 2-10C alkynyl groups, with examples including methyl, ethyl, propyl, cyclopropyl, allyl, propargyl and benzyl groups. Suitable examples of an aryl group represented by R17, R18 and R19 each includes those containing 6 to 30 carbon atoms, preferably 6-12C monocyclic or condensed-ring aryl groups, such as phenyl and naphthyl groups. The heterocyclic groups which R17, R18 and R19 can represent are 3- to 10-membered saturated or unsaturated heterocyclic groups containing at least one nitrogen, oxygen or sulfur atom as a hetero atom. These groups may be monocyclic, or they may form condensed rings by being fused together with other aromatic rings. Preferably, the heterocyclic groups are 5- or 6-membered aromatic heterocyclic groups, such as pyridyl, imidazolyl, quinolyl, benzimidazolyl, pyrimidyl, pyrazolyl, isoquinolyl, thiazolyl, thienyl, furyl and benzothiazolyl.
The alkyl, alkenyl, alkynyl, aryl and heterocyclic groups which R20 can represent have the same meanings as those which R17, R18 and R19 each can represent. The alkyl, alkenyl, alkynyl, aryl and heterocyclic groups which R59 and R60 each can represent in the NR59R60 group as R20 have the same meanings as those which R17, R18 and R19 each can represent, too.
Each of the groups represented by R17, R18, R19, R20, R59 and R60 may be substituted by the substituent Y recited hereinbefore.
In formula (VI), R17 and R18, R17 and R19, R19 and R20, or R20 and R18 may combine with each other to complete a ring.
When n is 0 in formula (VI), the desirable R17, R18 and R19 include 1-10C alkyl groups, 2-10C alkenyl groups, 2-10C alkynyl groups, 6-10C aryl groups and nitrogen-containing heterocyclic groups, and the desirable R20 includes a hydrogen atom, 1-10C alkyl groups, 2-10C alkenyl groups, 2-10C alkynyl groups, 6-10C aryl groups and nitrogen-containing heterocyclic groups. Preferably, R17, R18 and R19 each is a group selected from 1-10C alkyl groups, 2-10C alkenyl groups, 2-10C alkynyl groups, 6-10C aryl groups or nitrogen-containing heterocyclic groups, and R20 is a hydrogen atom.
When n is 1 in formula (VI), the desirable R17, R18 and R19 include a hydrogen atom, 1-10C alkyl groups, 2-10C alkenyl groups, 2-10C alkynyl groups, 6-10C aryl groups and nitrogen-containing heterocyclic groups, the desirable L1 is xe2x80x94COxe2x80x94, and the desirable R20 includes a hydrogen atom, 1-10C alkyl groups, 2-10C alkenyl groups, 2-10C alkynyl groups, 6-10C aryl groups, nitrogen-containing heterocyclic groups and NR59R60. Therein, R59 is preferably a hydrogen atom, a hydroxyl group, an amino group, a 1-10C alkyl group, a 2-10C alkenyl group, a 2-10C alkynyl group, a 6-10C aryl group or a nitrogen-containing heterocyclic group, while R60 is preferably a hydrogen atom, a 1-10C alkyl group, a 2-10C alkenyl group, an alkynyl group, 6-10C aryl group or a heterocyclic group. In particular, it is advantageous that R17 be a 6-10C aryl group, both R18 and R19 be hydrogen atoms, L1 be xe2x80x94COxe2x80x94, R20 be NR59R60 and R59 be a hydrogen atom, a hydroxyl group, a 1-10C alkyl group, an alkenyl group or an alkynyl group.
Examples of a compound represented by formula (VI) are illustrated below, but these examples should not be construed as limiting the scope of the invention. 
The compounds represented by formula (VI) are available with each as commercial chemicals, or can be synthesized from commercial chemicals by the use of known methods. For syntheses of the compounds represented by formula (VI) can be adopted the methods described, e.g., in J. Amer. Chem. Soc., vol. 72, p. 2762 (1950), Organic Synthesis, vol. 2, p. 395, and Shin Jikken Kagaku Koza, vol. 14-2 and 14-3, Maruzen, Tokyo (1977), or the methods following them.
It is desirable that the compounds represented by formula (VI) be added to a layer adjacent to or other than an emulsion layer by incorporating them in a coating composition for forming such a layer before or at the time when the coating composition is coated, and then allowed to be dispersed into the emulsion layer. However, they may be added to an emulsion during the emulsion-making, specifically before, during or after chemical sensitization.
The appropriate addition amount of those compounds, though it depends largely on the addition method adopted and the species of the compound(s) added, is generally from 5xc3x9710xe2x88x926 to 0.05 mole, preferably from 1xc3x9710xe2x88x925 to 0.005 mole, per mole of light-sensitive silver halide. When the amount added is greater than the foregoing upper limit, undesirable results, including an increase in fog, are produced.
In adding the compounds represented by formula (VI), it is desirable that they be dissolved in a solvent soluble in water. The pH of their solutions may be lowered or heightened by adding thereto an acid or a base. On the other hand, the surfactants may be present therein. Those compounds may be dissolved in high boiling organic solvents and added as emulsified dispersions, or they may be made into microcrystalline dispersions according to known methods and then added.
The compounds represented by formula (VI) may be used as a mixture of two or more thereof. When they are used as a mixture of two or more thereof, they may be added to the same layer or separate layers.
With respect to the ranking of the compounds represented by formulae (II) to (VI), the following is the descending order of suitability for the invention:
(V-1) greater than (V-2) greater than (V-3) greater than (VI) greater than (II) greater than (III) greater than (IV-1) greater than (IV-2)
The silver halide emulsions usable in the present photographic light-sensitive material include high chloride-content silver halide emulsions and silver iodobromide emulsions. In particular, (111) AgBrI tabular emulsions (iodide content: 1-20 mole %) are preferred over the others.
The suitable grain size and thickness of the tabular emulsions are from 0.2 to 5 xcexcm (equivalent-circle diameter) and from 0.01 to 0.1 xcexcm respectively. The appropriate variation coefficients of grain size distribution and grain thickness distribution are each at most 20%, preferably from 10 to 15% And the suitable aspect ratio is from 3 to 30.
The tabular silver iodobromide emulsions suitable for the invention can be made by reference to U.S. Pat. Nos. 4,439,520, 4,434,226, 4,433,048, 4,414,310 and 5,334,495.
And the very thin tabular emulsions having a grain thickness of at most 0.1 xcexcm can be made by reference to U.S. Pat. Nos. 5,460,928, 5,411,853 and 5,418,125.
The high chloride-content tabular silver halide emulsions suitable for the invention can be prepared by reference to European Patent Nos. 723,187, 619,517, 534,395 and 584,644.
For details of the color couplers used in the invention, the description in JP-A-11-65007, paragraph Nos. 0019 to 0024, can be referred to. For details of the chemical sensitization applicable to the invention, the description in the above gazette, paragraph Nos. 0041 to 0053, can be referred to. For details of the antifoggants usable in the invention, the description in the above gazette, paragraph No. 0057, can be referred to. For details of the sensitizing dyes usable in the invention, the description in the above gazette, paragraph Nos. 0058 to 0060, can be referred to. For details of the photographic development processing applicable to the invention, the description in the above gazette, paragraph Nos. 0080 to 0099, can be referred to. For details of the APS system application to the invention, the description in the above gazette, paragraph Nos. 0100 to0126, can be referred to.